Improve exceptions (#1256)

- Kick more exceptions further up the pipeline to be more likely to be shown to player
- Try to avoid lots of console spamming when it's the same error multiple times
- Allow parsing of FaweExceptions during commands to better give information to players

worldedit-core/src/main/java/com/fastasyncworldedit/core/Fawe.java

@@ -1,6 +1,7 @@
 package com.fastasyncworldedit.core;
 
 import com.fastasyncworldedit.core.configuration.Settings;
+import com.fastasyncworldedit.core.internal.exception.FaweException;
 import com.fastasyncworldedit.core.queue.implementation.QueueHandler;
 import com.fastasyncworldedit.core.util.CachedTextureUtil;
 import com.fastasyncworldedit.core.util.CleanTextureUtil;
@@ -346,4 +347,50 @@ public class Fawe {
         return this.thread = Thread.currentThread();
     }
 
+    /**
+     * Non-api. Handles an input FAWE exception if not already handled, given the input boolean array.
+     * Looks at the {@link FaweException.Type} and decides what to do (rethrows if we want to attempt to show the error to the
+     * player, outputs to console where necessary).
+     *  @param faweExceptionReasonsUsed boolean array that should be cached where this method is called from of length {@code
+     *                                 FaweException.Type.values().length}
+     * @param e                        {@link FaweException} to handle
+     * @param logger                   {@link Logger} of the calling class
+     */
+    public static void handleFaweException(
+            boolean[] faweExceptionReasonsUsed,
+            FaweException e,
+            final Logger logger
+    ) {
+        FaweException.Type type = e.getType();
+        switch (type) {
+            case OTHER:
+                logger.catching(e);
+                throw e;
+            case LOW_MEMORY:
+                if (!faweExceptionReasonsUsed[type.ordinal()]) {
+                    logger.warn("FaweException: " + e.getMessage());
+                    faweExceptionReasonsUsed[type.ordinal()] = true;
+                    throw e;
+                }
+            case MAX_TILES:
+            case NO_REGION:
+            case MAX_CHECKS:
+            case MAX_CHANGES:
+            case MAX_ENTITIES:
+            case MAX_ITERATIONS:
+            case OUTSIDE_REGION:
+                if (!faweExceptionReasonsUsed[type.ordinal()]) {
+                    faweExceptionReasonsUsed[type.ordinal()] = true;
+                    throw e;
+                } else {
+                    return;
+                }
+            default:
+                if (!faweExceptionReasonsUsed[type.ordinal()]) {
+                    faweExceptionReasonsUsed[type.ordinal()] = true;
+                    logger.warn("FaweException: " + e.getMessage());
+                }
+        }
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/FaweCache.java

@@ -3,8 +3,8 @@ package com.fastasyncworldedit.core;
 import com.fastasyncworldedit.core.configuration.Caption;
 import com.fastasyncworldedit.core.configuration.Settings;
 import com.fastasyncworldedit.core.internal.exception.FaweBlockBagException;
-import com.fastasyncworldedit.core.internal.exception.FaweChunkLoadException;
 import com.fastasyncworldedit.core.internal.exception.FaweException;
+import com.fastasyncworldedit.core.internal.exception.FaweException.Type;
 import com.fastasyncworldedit.core.math.BitArray;
 import com.fastasyncworldedit.core.math.BitArrayUnstretched;
 import com.fastasyncworldedit.core.math.MutableBlockVector3;
@@ -132,20 +132,40 @@ public enum FaweCache implements Trimable {
     /*
     Exceptions
      */
-    public static final FaweChunkLoadException CHUNK = new FaweChunkLoadException();
     public static final FaweBlockBagException BLOCK_BAG = new FaweBlockBagException();
-    public static final FaweException MANUAL = new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.manual"));
-    public static final FaweException NO_REGION = new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.no.region"));
+    public static final FaweException MANUAL = new FaweException(
+            Caption.of("fawe.cancel.worldedit.cancel.reason.manual"),
+            Type.MANUAL
+    );
+    public static final FaweException NO_REGION = new FaweException(
+            Caption.of("fawe.cancel.worldedit.cancel.reason.no.region"),
+            Type.NO_REGION
+    );
     public static final FaweException OUTSIDE_REGION = new FaweException(Caption.of(
-            "fawe.cancel.worldedit.cancel.reason.outside.region"));
-    public static final FaweException MAX_CHECKS = new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.max.checks"));
-    public static final FaweException MAX_CHANGES = new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.max.changes"));
-    public static final FaweException LOW_MEMORY = new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.low.memory"));
+            "fawe.cancel.worldedit.cancel.reason.outside.region"),
+            Type.OUTSIDE_REGION);
+    public static final FaweException MAX_CHECKS = new FaweException(
+            Caption.of("fawe.cancel.worldedit.cancel.reason.max" + ".checks"),
+            Type.MAX_CHECKS
+    );
+    public static final FaweException MAX_CHANGES = new FaweException(
+            Caption.of("fawe.cancel.worldedit.cancel.reason.max" + ".changes"),
+            Type.MAX_CHANGES
+    );
+    public static final FaweException LOW_MEMORY = new FaweException(
+            Caption.of("fawe.cancel.worldedit.cancel.reason.low" + ".memory"),
+            Type.LOW_MEMORY
+    );
     public static final FaweException MAX_ENTITIES = new FaweException(Caption.of(
-            "fawe.cancel.worldedit.cancel.reason.max.entities"));
-    public static final FaweException MAX_TILES = new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.max.tiles"));
+            "fawe.cancel.worldedit.cancel.reason.max.entities"),
+            Type.MAX_ENTITIES);
+    public static final FaweException MAX_TILES = new FaweException(Caption.of(
+            "fawe.cancel.worldedit.cancel.reason.max.tiles",
+            Type.MAX_TILES
+    ));
     public static final FaweException MAX_ITERATIONS = new FaweException(Caption.of(
-            "fawe.cancel.worldedit.cancel.reason.max.iterations"));
+            "fawe.cancel.worldedit.cancel.reason.max.iterations"),
+            Type.MAX_ITERATIONS);
 
     /*
     thread cache
@@ -539,28 +559,55 @@ public enum FaweCache implements Trimable {
                 Executors.defaultThreadFactory(),
                 new ThreadPoolExecutor.CallerRunsPolicy()
         ) {
-            protected void afterExecute(Runnable r, Throwable t) {
+
+            // Array for lazy avoidance of concurrent modification exceptions and needless overcomplication of code (synchronisation is
+            // not very important)
+            private final boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
+            private int lastException = Integer.MIN_VALUE;
+            private int count = 0;
+
+            protected synchronized void afterExecute(Runnable runnable, Throwable throwable) {
+                super.afterExecute(runnable, throwable);
+                if (throwable == null && runnable instanceof Future<?>) {
                     try {
-                    super.afterExecute(r, t);
-                    if (t == null && r instanceof Future<?>) {
-                        try {
-                            Future<?> future = (Future<?>) r;
+                        Future<?> future = (Future<?>) runnable;
                         if (future.isDone()) {
                             future.get();
                         }
                     } catch (CancellationException ce) {
-                            t = ce;
+                        throwable = ce;
                     } catch (ExecutionException ee) {
-                            t = ee.getCause();
+                        throwable = ee.getCause();
                     } catch (InterruptedException ie) {
                         Thread.currentThread().interrupt();
                     }
                 }
-                    if (t != null) {
-                        t.printStackTrace();
+                if (throwable != null) {
+                    if (throwable instanceof FaweException) {
+                        handleFaweException((FaweException) throwable);
+                    } else if (throwable.getCause() instanceof FaweException) {
+                        handleFaweException((FaweException) throwable.getCause());
+                    } else {
+                        int hash = throwable.getMessage().hashCode();
+                        if (hash != lastException) {
+                            lastException = hash;
+                            LOGGER.catching(throwable);
+                            count = 0;
+                        } else if (count < Settings.IMP.QUEUE.PARALLEL_THREADS) {
+                            LOGGER.warn(throwable.getMessage());
+                            count++;
                         }
-                } catch (Throwable e) {
-                    e.printStackTrace();
+                    }
+                }
+            }
+
+            private void handleFaweException(FaweException e) {
+                FaweException.Type type = e.getType();
+                if (e.getType() == FaweException.Type.OTHER) {
+                    LOGGER.catching(e);
+                } else if (!faweExceptionReasonsUsed[type.ordinal()]) {
+                    faweExceptionReasonsUsed[type.ordinal()] = true;
+                    LOGGER.warn("FaweException: " + e.getMessage());
                 }
             }
         };

worldedit-core/src/main/java/com/fastasyncworldedit/core/command/tool/brush/CatenaryBrush.java

@@ -60,11 +60,7 @@ public class CatenaryBrush implements Brush, ResettableTool {
         }
         List<BlockVector3> nodes = Arrays.asList(pos1, vertex, pos2);
         vertex = null;
-        try {
         editSession.drawSpline(pattern, nodes, 0, 0, 0, 10, size, !shell);
-        } catch (WorldEditException e) {
-            e.printStackTrace();
-        }
         player.print(Caption.of("fawe.worldedit.brush.brush.line.secondary"));
         if (!select) {
             pos1 = null;

worldedit-core/src/main/java/com/fastasyncworldedit/core/command/tool/brush/SurfaceSpline.java

@@ -78,11 +78,7 @@ public class SurfaceSpline implements Brush {
             }
             if (radius == 0) {
                 BlockVector3 set = mutable.setComponents(tipx, tipy, tipz);
-                try {
                 pattern.apply(editSession, set, set);
-                } catch (WorldEditException e) {
-                    e.printStackTrace();
-                }
             } else {
                 vset.add(tipx, tipy, tipz);
             }

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/processor/MultiBatchProcessor.java

@@ -1,6 +1,9 @@
 package com.fastasyncworldedit.core.extent.processor;
 
+import com.fastasyncworldedit.core.Fawe;
 import com.fastasyncworldedit.core.FaweCache;
+import com.fastasyncworldedit.core.configuration.Settings;
+import com.fastasyncworldedit.core.internal.exception.FaweException;
 import com.fastasyncworldedit.core.queue.Filter;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
 import com.fastasyncworldedit.core.queue.IChunk;
@@ -9,6 +12,8 @@ import com.fastasyncworldedit.core.queue.IChunkSet;
 import com.fastasyncworldedit.core.util.StringMan;
 import com.google.common.cache.LoadingCache;
 import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import org.apache.logging.log4j.Logger;
 
 import javax.annotation.Nullable;
 import java.util.ArrayList;
@@ -26,9 +31,16 @@ import java.util.function.Supplier;
 
 public class MultiBatchProcessor implements IBatchProcessor {
 
-    private IBatchProcessor[] processors;
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
     private final LoadingCache<Class<?>, Map<Long, Filter>> classToThreadIdToFilter =
             FaweCache.IMP.createCache((Supplier<Map<Long, Filter>>) ConcurrentHashMap::new);
+    // Array for lazy avoidance of concurrent modification exceptions and needless overcomplication of code (synchronisation is
+    // not very important)
+    private boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
+    private IBatchProcessor[] processors;
+    private int lastException = Integer.MIN_VALUE;
+    private int exceptionCount = 0;
 
     public MultiBatchProcessor(IBatchProcessor... processors) {
         this.processors = processors;
@@ -72,7 +84,6 @@ public class MultiBatchProcessor implements IBatchProcessor {
     @Override
     public IChunkSet processSet(IChunk chunk, IChunkGet get, IChunkSet set) {
         Map<Integer, Set<IBatchProcessor>> ordered = new HashMap<>();
-        try {
         IChunkSet chunkSet = set;
         for (IBatchProcessor processor : processors) {
             if (processor.getScope() != ProcessorScope.ADDING_BLOCKS) {
@@ -103,10 +114,6 @@ public class MultiBatchProcessor implements IBatchProcessor {
             }
         }
         return chunkSet;
-        } catch (Throwable e) {
-            e.printStackTrace();
-            throw e;
-        }
     }
 
     @Nullable
@@ -139,7 +146,22 @@ public class MultiBatchProcessor implements IBatchProcessor {
             }
             return CompletableFuture.completedFuture(set);
         } catch (Throwable e) {
-            e.printStackTrace();
+            if (e instanceof FaweException) {
+                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) e, LOGGER);
+            } else if (e.getCause() instanceof FaweException) {
+                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) e.getCause(), LOGGER);
+            } else {
+                String message = e.getMessage();
+                int hash = message.hashCode();
+                if (lastException != hash) {
+                    lastException = hash;
+                    exceptionCount = 0;
+                    LOGGER.catching(e);
+                } else if (exceptionCount < Settings.IMP.QUEUE.PARALLEL_THREADS) {
+                    exceptionCount++;
+                    LOGGER.warn(message);
+                }
+            }
             return null;
         }
     }
@@ -214,4 +236,16 @@ public class MultiBatchProcessor implements IBatchProcessor {
         return ProcessorScope.valueOf(0);
     }
 
+    /**
+     * Sets the cached boolean array of length {@code FaweException.Type.values().length} that determines if a thrown
+     * {@link FaweException} of type {@link FaweException.Type} should be output to console, rethrown to attempt to be visible
+     * to the player, etc. Allows the same array to be used as widely as possible across the edit to avoid spam to console.
+     *
+     * @param faweExceptionReasonsUsed boolean array that should be cached where this method is called from of length {@code
+     *                                 FaweException.Type.values().length}
+     */
+    public void setFaweExceptionArray(final boolean[] faweExceptionReasonsUsed) {
+        this.faweExceptionReasonsUsed = faweExceptionReasonsUsed;
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/processor/heightmap/HeightMap.java

@@ -10,6 +10,7 @@ import com.sk89q.worldedit.regions.CuboidRegion;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.util.Location;
 
+import java.lang.reflect.InvocationTargetException;
 import java.util.concurrent.ThreadLocalRandom;
 
 public interface HeightMap {
@@ -60,7 +61,7 @@ public interface HeightMap {
                         .getConstructors()[0].newInstance(5, 1));
                 int diameter = 2 * size + 1;
                 data[1] = filter.filter(data[1], diameter, diameter);
-            } catch (Throwable e) {
+            } catch (IllegalAccessException | InvocationTargetException | InstantiationException e) {
                 e.printStackTrace();
             }
         }

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/processor/lighting/NMSRelighter.java

@@ -864,7 +864,6 @@ public class NMSRelighter implements Relighter {
         if (isEmpty()) {
             return;
         }
-        try {
         if (sky) {
             fixSkyLighting();
         } else {
@@ -880,9 +879,6 @@ public class NMSRelighter implements Relighter {
         }
         fixBlockLighting();
         sendChunks();
-        } catch (Throwable e) {
-            e.printStackTrace();
-        }
     }
 
     public void fixBlockLighting() {
@@ -930,11 +926,7 @@ public class NMSRelighter implements Relighter {
     }
 
     public void flush() {
-        try {
         close();
-        } catch (Exception e) {
-            e.printStackTrace();
-        }
     }
 
     public synchronized void sendChunks() {

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/mask/AngleMask.java

@@ -59,7 +59,6 @@ public class AngleMask extends SolidBlockMask implements ResettableMask {
 
     public int getHeight(Extent extent, int x, int y, int z) {
         //        return extent.getNearestSurfaceTerrainBlock(x, z, y, 0, maxY);
-        try {
         int rx = x - cacheBotX + 16;
         int rz = z - cacheBotZ + 16;
         int index;
@@ -82,10 +81,6 @@ public class AngleMask extends SolidBlockMask implements ResettableMask {
             cacheHeights[index] = (byte) (result = lastY = extent.getNearestSurfaceTerrainBlock(x, z, lastY, minY, maxY));
         }
         return result;
-        } catch (Throwable e) {
-            e.printStackTrace();
-            throw e;
-        }
     }
 
     protected boolean testSlope(Extent extent, int x, int y, int z) {

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/ExpressionPattern.java

@@ -54,9 +54,6 @@ public class ExpressionPattern extends AbstractPattern {
         } catch (EvaluationException e) {
             e.printStackTrace();
             return BlockTypes.AIR.getDefaultState().toBaseBlock();
-        } catch (Throwable e) {
-            e.printStackTrace();
-            throw e;
         }
     }
 

worldedit-core/src/main/java/com/fastasyncworldedit/core/internal/exception/FaweBlockBagException.java

@@ -5,7 +5,7 @@ import com.fastasyncworldedit.core.configuration.Caption;
 public class FaweBlockBagException extends FaweException {
 
     public FaweBlockBagException() {
-        super(Caption.of("fawe.error.worldedit.some.fails.blockbag"));
+        super(Caption.of("fawe.error.worldedit.some.fails.blockbag"), Type.BLOCK_BAG);
     }
 
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/internal/exception/FaweChunkLoadException.java

@@ -1,11 +0,0 @@
-package com.fastasyncworldedit.core.internal.exception;
-
-import com.fastasyncworldedit.core.configuration.Caption;
-
-public class FaweChunkLoadException extends FaweException {
-
-    public FaweChunkLoadException() {
-        super(Caption.of("fawe.cancel.worldedit.failed.load.chunk"));
-    }
-
-}

worldedit-core/src/main/java/com/fastasyncworldedit/core/internal/exception/FaweException.java

@@ -13,13 +13,28 @@ public class FaweException extends RuntimeException {
     public static final FaweException _disableQueue = new FaweException("disableQueue");
 
     private final Component message;
+    private final Type type;
 
+    /**
+     * New instance. Defaults to {@link FaweException.Type#OTHER}.
+     */
     public FaweException(String reason) {
         this(TextComponent.of(reason));
     }
 
+    /**
+     * New instance. Defaults to {@link FaweException.Type#OTHER}.
+     */
     public FaweException(Component reason) {
+        this(reason, Type.OTHER);
+    }
+
+    /**
+     * New instance of a given {@link FaweException.Type}
+     */
+    public FaweException(Component reason, Type type) {
         this.message = reason;
+        this.type = type;
     }
 
     @Override
@@ -31,6 +46,14 @@ public class FaweException extends RuntimeException {
         return message;
     }
 
+    /**
+     * Get the {@link FaweException.Type}
+     * @return the {@link FaweException.Type}
+     */
+    public Type getType() {
+        return type;
+    }
+
     public static FaweException get(Throwable e) {
         if (e instanceof FaweException) {
             return (FaweException) e;
@@ -52,4 +75,19 @@ public class FaweException extends RuntimeException {
         return this;
     }
 
+    public enum Type {
+        MANUAL,
+        NO_REGION,
+        OUTSIDE_REGION,
+        MAX_CHECKS,
+        MAX_CHANGES,
+        LOW_MEMORY,
+        MAX_ENTITIES,
+        MAX_TILES,
+        MAX_ITERATIONS,
+        BLOCK_BAG,
+        CHUNK,
+        OTHER
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/ParallelQueueExtent.java

@@ -1,5 +1,6 @@
 package com.fastasyncworldedit.core.queue.implementation;
 
+import com.fastasyncworldedit.core.Fawe;
 import com.fastasyncworldedit.core.FaweCache;
 import com.fastasyncworldedit.core.configuration.Settings;
 import com.fastasyncworldedit.core.extent.NullExtent;
@@ -10,7 +11,9 @@ import com.fastasyncworldedit.core.extent.filter.DistrFilter;
 import com.fastasyncworldedit.core.extent.filter.LinkedFilter;
 import com.fastasyncworldedit.core.extent.filter.block.ChunkFilterBlock;
 import com.fastasyncworldedit.core.extent.processor.BatchProcessorHolder;
+import com.fastasyncworldedit.core.extent.processor.MultiBatchProcessor;
 import com.fastasyncworldedit.core.function.mask.BlockMaskBuilder;
+import com.fastasyncworldedit.core.internal.exception.FaweException;
 import com.fastasyncworldedit.core.queue.Filter;
 import com.fastasyncworldedit.core.queue.IQueueChunk;
 import com.fastasyncworldedit.core.queue.IQueueExtent;
@@ -22,6 +25,7 @@ import com.sk89q.worldedit.function.mask.ExistingBlockMask;
 import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.function.pattern.BlockPattern;
 import com.sk89q.worldedit.function.pattern.Pattern;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
@@ -31,6 +35,7 @@ import com.sk89q.worldedit.world.block.BaseBlock;
 import com.sk89q.worldedit.world.block.BlockState;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
 import com.sk89q.worldedit.world.block.BlockType;
+import org.apache.logging.log4j.Logger;
 
 import java.util.Iterator;
 import java.util.List;
@@ -40,19 +45,32 @@ import java.util.stream.IntStream;
 
 public class ParallelQueueExtent extends PassthroughExtent implements IQueueWrapper {
 
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
     private final World world;
     private final QueueHandler handler;
     private final BatchProcessorHolder processor;
     private final BatchProcessorHolder postProcessor;
+    // Array for lazy avoidance of concurrent modification exceptions and needless overcomplication of code (synchronisation is
+    // not very important)
+    private final boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
     private int changes;
     private final boolean fastmode;
+    private int lastException = Integer.MIN_VALUE;
+    private int exceptionCount = 0;
 
     public ParallelQueueExtent(QueueHandler handler, World world, boolean fastmode) {
         super(handler.getQueue(world, new BatchProcessorHolder(), new BatchProcessorHolder()));
         this.world = world;
         this.handler = handler;
         this.processor = (BatchProcessorHolder) getExtent().getProcessor();
+        if (this.processor.getProcessor() instanceof MultiBatchProcessor) {
+            ((MultiBatchProcessor) this.processor.getProcessor()).setFaweExceptionArray(faweExceptionReasonsUsed);
+        }
         this.postProcessor = (BatchProcessorHolder) getExtent().getPostProcessor();
+        if (this.postProcessor.getProcessor() instanceof MultiBatchProcessor) {
+            ((MultiBatchProcessor) this.postProcessor.getProcessor()).setFaweExceptionArray(faweExceptionReasonsUsed);
+        }
         this.fastmode = fastmode;
     }
 
@@ -99,9 +117,11 @@ public class ParallelQueueExtent extends PassthroughExtent implements IQueueWrap
                 try {
                     final Filter newFilter = filter.fork();
                     // Create a chunk that we will reuse/reset for each operation
-                    final IQueueExtent<IQueueChunk> queue = getNewQueue();
+                    final SingleThreadQueueExtent queue = (SingleThreadQueueExtent) getNewQueue();
                     queue.setFastMode(fastmode);
+                    queue.setFaweExceptionArray(faweExceptionReasonsUsed);
                     synchronized (queue) {
+                        try {
                             ChunkFilterBlock block = null;
 
                             while (true) {
@@ -119,9 +139,27 @@ public class ParallelQueueExtent extends PassthroughExtent implements IQueueWrap
                                 block = queue.apply(block, newFilter, region, chunkX, chunkZ, full);
                             }
                             queue.flush();
+                        } catch (Throwable t) {
+                            if (t instanceof FaweException) {
+                                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) t, LOGGER);
+                            } else if (t.getCause() instanceof FaweException) {
+                                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) t.getCause(), LOGGER);
+                            } else {
+                                throw t;
+                            }
+                        }
                     }
                 } catch (Throwable e) {
-                    e.printStackTrace();
+                    String message = e.getMessage();
+                    int hash = message.hashCode();
+                    if (lastException != hash) {
+                        lastException = hash;
+                        exceptionCount = 0;
+                        LOGGER.catching(e);
+                    } else if (exceptionCount < Settings.IMP.QUEUE.PARALLEL_THREADS) {
+                        exceptionCount++;
+                        LOGGER.warn(message);
+                    }
                 }
             })).toArray(ForkJoinTask[]::new);
             // Join filters

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/SingleThreadQueueExtent.java

@@ -41,8 +41,9 @@ import java.util.concurrent.locks.ReentrantLock;
  * Single threaded implementation for IQueueExtent (still abstract) - Does not implement creation of
  * chunks (that has to implemented by the platform e.g., Bukkit)
  * <p>
- * This queue is reusable {@link #init(Extent, IChunkCache, IChunkCache)} }
+ * This queue is reusable {@link #init(Extent, IChunkCache, IChunkCache)}
  */
+@SuppressWarnings({"unchecked", "rawtypes"})
 public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implements IQueueExtent<IQueueChunk> {
 
     private static final Logger LOGGER = LogManagerCompat.getLogger();
@@ -51,28 +52,28 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
     // private static final ConcurrentLinkedQueue<IChunk> CHUNK_POOL = new ConcurrentLinkedQueue<>();
     // Chunks currently being queued / worked on
     private final Long2ObjectLinkedOpenHashMap<IQueueChunk> chunks = new Long2ObjectLinkedOpenHashMap<>();
-
+    private final ConcurrentLinkedQueue<Future> submissions = new ConcurrentLinkedQueue<>();
+    private final ReentrantLock getChunkLock = new ReentrantLock();
     private World world = null;
     private int minY = 0;
     private int maxY = 255;
-
     private IChunkCache<IChunkGet> cacheGet;
     private IChunkCache<IChunkSet> cacheSet;
     private boolean initialized;
-
     private Thread currentThread;
-    private final ConcurrentLinkedQueue<Future> submissions = new ConcurrentLinkedQueue<>();
     // Last access pointers
     private IQueueChunk lastChunk;
     private long lastPair = Long.MAX_VALUE;
-
     private boolean enabledQueue = true;
-
     private boolean fastmode = false;
+    // Array for lazy avoidance of concurrent modification exceptions and needless overcomplication of code (synchronisation is
+    // not very important)
+    private boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
+    private int lastException = Integer.MIN_VALUE;
+    private int exceptionCount = 0;
 
-    private final ReentrantLock getChunkLock = new ReentrantLock();
-
-    public SingleThreadQueueExtent() {}
+    public SingleThreadQueueExtent() {
+    }
 
     /**
      * New instance given inclusive world height bounds.
@@ -114,13 +115,13 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
     }
 
     @Override
-    public void setFastMode(boolean fastmode) {
-        this.fastmode = fastmode;
+    public boolean isFastMode() {
+        return fastmode;
     }
 
     @Override
-    public boolean isFastMode() {
-        return fastmode;
+    public void setFastMode(boolean fastmode) {
+        this.fastmode = fastmode;
     }
 
     @Override
@@ -133,6 +134,18 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         return maxY;
     }
 
+    /**
+     * Sets the cached boolean array of length {@code FaweException.Type.values().length} that determines if a thrown
+     * {@link FaweException} of type {@link FaweException.Type} should be output to console, rethrown to attempt to be visible
+     * to the player, etc. Allows the same array to be used as widely as possible across the edit to avoid spam to console.
+     *
+     * @param faweExceptionReasonsUsed boolean array that should be cached where this method is called from of length {@code
+     *                                 FaweException.Type.values().length}
+     */
+    public void setFaweExceptionArray(final boolean[] faweExceptionReasonsUsed) {
+        this.faweExceptionReasonsUsed = faweExceptionReasonsUsed;
+    }
+
     /**
      * Resets the queue.
      */
@@ -372,41 +385,11 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         if (aggressive) {
             if (targetSize == 0) {
                 while (!submissions.isEmpty()) {
-                    Future future = submissions.poll();
-                    try {
-                        while (future != null) {
-                            future = (Future) future.get();
-                        }
-                    } catch (FaweException messageOnly) {
-                        LOGGER.warn(messageOnly.getMessage());
-                    } catch (ExecutionException e) {
-                        if (e.getCause() instanceof FaweException) {
-                            LOGGER.warn(e.getCause().getClass().getCanonicalName() + ": " + e.getCause().getMessage());
-                        } else {
-                            e.printStackTrace();
-                        }
-                    } catch (InterruptedException e) {
-                        e.printStackTrace();
-                    }
+                    iterateSubmissions();
                 }
             }
             for (int i = 0; i < overflow; i++) {
-                Future first = submissions.poll();
-                try {
-                    while (first != null) {
-                        first = (Future) first.get();
-                    }
-                } catch (FaweException messageOnly) {
-                    LOGGER.warn(messageOnly.getMessage());
-                } catch (ExecutionException e) {
-                    if (e.getCause() instanceof FaweException) {
-                        LOGGER.warn(e.getCause().getClass().getCanonicalName() + ": " + e.getCause().getMessage());
-                    } else {
-                        e.printStackTrace();
-                    }
-                } catch (InterruptedException e) {
-                    e.printStackTrace();
-                }
+                iterateSubmissions();
             }
         } else {
             for (int i = 0; i < overflow; i++) {
@@ -416,19 +399,23 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
                         Future after = null;
                         try {
                             after = (Future) next.get();
-                        } catch (FaweException messageOnly) {
-                            LOGGER.warn(messageOnly.getMessage());
-                        } catch (ExecutionException e) {
+                        } catch (FaweException e) {
+                            Fawe.handleFaweException(faweExceptionReasonsUsed, e, LOGGER);
+                        } catch (ExecutionException | InterruptedException e) {
                             if (e.getCause() instanceof FaweException) {
-                                LOGGER.warn(e.getCause().getClass().getCanonicalName() + ": " + e.getCause().getMessage());
+                                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) e.getCause(), LOGGER);
                             } else {
-                                e.printStackTrace();
+                                String message = e.getMessage();
+                                int hash = message.hashCode();
+                                if (lastException != hash) {
+                                    lastException = hash;
+                                    exceptionCount = 0;
+                                    LOGGER.catching(e);
+                                } else if (exceptionCount < Settings.IMP.QUEUE.PARALLEL_THREADS) {
+                                    exceptionCount++;
+                                    LOGGER.warn(message);
+                                }
                             }
-                            LOGGER.error(
-                                    "Please report this error on our issue tracker: https://github.com/IntellectualSites/FastAsyncWorldEdit/issues");
-                            e.getCause().printStackTrace();
-                        } catch (InterruptedException e) {
-                            e.printStackTrace();
                         } finally {
                             /*
                              * If the execution failed, namely next.get() threw an exception,
@@ -446,6 +433,32 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         }
     }
 
+    private void iterateSubmissions() {
+        Future first = submissions.poll();
+        try {
+            while (first != null) {
+                first = (Future) first.get();
+            }
+        } catch (FaweException e) {
+            Fawe.handleFaweException(faweExceptionReasonsUsed, e, LOGGER);
+        } catch (ExecutionException | InterruptedException e) {
+            if (e.getCause() instanceof FaweException) {
+                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) e.getCause(), LOGGER);
+            } else {
+                String message = e.getMessage();
+                int hash = message.hashCode();
+                if (lastException != hash) {
+                    lastException = hash;
+                    exceptionCount = 0;
+                    LOGGER.catching(e);
+                } else if (exceptionCount < Settings.IMP.QUEUE.PARALLEL_THREADS) {
+                    exceptionCount++;
+                    LOGGER.warn(message);
+                }
+            }
+        }
+    }
+
     @Override
     public synchronized void flush() {
         if (!chunks.isEmpty()) {

worldedit-core/src/main/java/com/sk89q/worldedit/command/ClipboardCommands.java

@@ -193,7 +193,7 @@ public class ClipboardCommands {
                 .getZ() + 1));
         FaweLimit limit = actor.getLimit();
         if (volume >= limit.MAX_CHECKS) {
-            throw new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.max.checks"));
+            throw FaweCache.MAX_CHECKS;
         }
         session.setClipboard(null);
         ReadOnlyClipboard lazyClipboard = ReadOnlyClipboard.of(region, !skipEntities, copyBiomes);
@@ -558,7 +558,7 @@ public class ClipboardCommands {
         PasteEvent event = new PasteEvent(player, clipboard, uri, editSession, to);
         WorldEdit.getInstance().getEventBus().post(event);
         if (event.isCancelled()) {
-            throw new FaweException(Caption.of("fawe.cancel.worldedit.cancel.reason.manual"));
+            throw FaweCache.MANUAL;
         }
     }
     //FAWE end

worldedit-core/src/main/java/com/sk89q/worldedit/command/GenerationCommands.java

@@ -601,7 +601,6 @@ public class GenerationCommands {
         int[] count = new int[1];
         final BufferedImage finalImage = image;
         RegionVisitor visitor = new RegionVisitor(region, pos -> {
-            try {
             int x = pos.getBlockX() - pos1.getBlockX();
             int z = pos.getBlockZ() - pos1.getBlockZ();
             int color = finalImage.getRGB(x, z);
@@ -611,10 +610,6 @@ public class GenerationCommands {
                 return editSession.setBlock(pos, block.getDefaultState());
             }
             return false;
-            } catch (Throwable e) {
-                e.printStackTrace();
-            }
-            return false;
         }, editSession);
         Operations.completeBlindly(visitor);
         actor.print(Caption.of("fawe.worldedit.visitor.visitor.block", editSession.getBlockChangeCount()));

worldedit-core/src/main/java/com/sk89q/worldedit/extension/platform/PlatformCommandManager.java

@@ -774,20 +774,19 @@ public final class PlatformCommandManager {
             }
             actor.printError(e.getRichMessage());
         } catch (CommandExecutionException e) {
+            handleUnknownException(actor, e.getCause());
+        } catch (CommandException e) {
             if (e.getCause() instanceof FaweException) {
                 actor.print(Caption.of("fawe.cancel.worldedit.cancel.reason", ((FaweException) e.getCause()).getComponent()));
             } else {
-                handleUnknownException(actor, e.getCause());
-            }
-        } catch (CommandException e) {
                 Component msg = e.getRichMessage();
                 if (msg != TextComponent.empty()) {
-                actor.print(TextComponent.builder("")
-                        .append(e.getRichMessage())
-                        .build());
-                List<String> argList = parseArgs(event.getArguments()).map(Substring::getSubstring).collect(Collectors.toList());
+                    List<String> argList = parseArgs(event.getArguments())
+                            .map(Substring::getSubstring)
+                            .collect(Collectors.toList());
                     printUsage(actor, argList);
                 }
+            }
         } catch (Throwable t) {
             handleUnknownException(actor, t);
         } finally {

worldedit-core/src/main/java/com/sk89q/worldedit/extent/clipboard/Clipboard.java

@@ -273,10 +273,9 @@ public interface Clipboard extends Extent, Iterable<BlockVector3>, Closeable {
         }
         try {
             Operations.completeLegacy(copy);
-        } catch (MaxChangedBlocksException e) {
-            e.printStackTrace();
+        } finally {
+            editSession.close(); // Make sure editsession is always closed
         }
-        editSession.flushQueue();
         return editSession;
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/internal/command/exception/WorldEditExceptionConverter.java

@@ -20,6 +20,7 @@
 package com.sk89q.worldedit.internal.command.exception;
 
 import com.fastasyncworldedit.core.configuration.Caption;
+import com.fastasyncworldedit.core.internal.exception.FaweException;
 import com.google.common.collect.ImmutableList;
 import com.sk89q.worldedit.DisallowedItemException;
 import com.sk89q.worldedit.EmptyClipboardException;
@@ -197,4 +198,11 @@ public class WorldEditExceptionConverter extends ExceptionConverterHelper {
         throw e;
     }
 
+    //FAWE start
+    @ExceptionMatch
+    public void convert(FaweException e) throws CommandException {
+        throw newCommandException(e.getComponent(), e);
+    }
+    //FAWE end
+
 }