Fix exceptions being squashed RegionVisitor preloading

worldedit-core/src/main/java/com/sk89q/worldedit/function/visitor/RegionVisitor.java

@@ -108,8 +108,7 @@ public class RegionVisitor implements Operation {
             int lastLeadChunkX = Integer.MIN_VALUE;
             int lastLeadChunkZ = Integer.MIN_VALUE;
             int loadingTarget = Settings.IMP.QUEUE.PRELOAD_CHUNK_COUNT;
-            try {
+            while (trailIter.hasNext()) {
-                for (; ; ) {
                 BlockVector3 pt = trailIter.next();
                 apply(pt);
                 int cx = pt.getBlockX() >> 4;
@@ -125,6 +124,8 @@ public class RegionVisitor implements Operation {
                     } else {
                         amount = 1;
                     }
+                    try {
+                        lead:
                         for (int count = 0; count < amount; ) {
                             BlockVector3 v = leadIter.next();
                             int vcx = v.getBlockX() >> 4;
@@ -136,51 +137,26 @@ public class RegionVisitor implements Operation {
                                 count++;
                             }
                             // Skip the next 15 blocks
-                            leadIter.next();
+                            for (int i = 0; i < 16; i++) {
-                            leadIter.next();
+                                if (!leadIter.hasNext()) {
-                            leadIter.next();
+                                    break lead;
-                            leadIter.next();
+                                }
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
-                            leadIter.next();
                                 leadIter.next();
                             }
                         }
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                    apply(trailIter.next());
-                }
                     } catch (FaweException e) {
+                        // Likely to be a low memory or cancellation exception.
                         throw new RuntimeException(e);
-            } catch (Throwable ignore) {
+                    } catch (Throwable ignored) {
+                        // Ignore as it is likely not something too important, and we can continue with the operation
+                    }
+                }
+                for (int i = 0; i < 16; i++) {
+                    if (!trailIter.hasNext()) {
+                        return null;
                     }
-            try {
-                for (; ; ) {
-                    apply(trailIter.next());
                     apply(trailIter.next());
                 }
-            } catch (FaweException e) {
-                throw new RuntimeException(e);
-            } catch (Throwable ignore) {
             }
         } else {
             for (BlockVector3 pt : region) {
@@ -188,7 +164,6 @@ public class RegionVisitor implements Operation {
             }
         }
         //FAWE end
-
         return null;
     }