fix: Add items to a player's inventory on the main thread (#1977)

- Fixes #1954

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/util/image/BukkitImageViewer.java

@@ -1,5 +1,6 @@
 package com.fastasyncworldedit.bukkit.util.image;
 
+import com.fastasyncworldedit.core.util.TaskManager;
 import com.fastasyncworldedit.core.util.image.Drawable;
 import com.fastasyncworldedit.core.util.image.ImageUtil;
 import com.fastasyncworldedit.core.util.image.ImageViewer;
@@ -163,15 +164,18 @@ public class BukkitImageViewer implements ImageViewer {
             controller.showInFrames(player, frames, true);
         } else {
             int slot = getMapSlot(player);
+            TaskManager.taskManager().sync(() -> {
                 if (slot == -1) {
                     if (initializing) {
                         player.getInventory().setItemInMainHand(new ItemStack(Material.MAP));
                     } else {
-                    return;
+                        return null;
                     }
                 } else if (player.getInventory().getHeldItemSlot() != slot) {
                     player.getInventory().setHeldItemSlot(slot);
                 }
+                return null;
+            });
             if (image == null && drawable != null) {
                 image = drawable.draw();
             }

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitPlayer.java

@@ -22,7 +22,6 @@ package com.sk89q.worldedit.bukkit;
 import com.fastasyncworldedit.core.configuration.Caption;
 import com.fastasyncworldedit.core.configuration.Settings;
 import com.fastasyncworldedit.core.util.TaskManager;
-import com.fastasyncworldedit.core.util.task.RunnableVal;
 import com.sk89q.util.StringUtil;
 import com.sk89q.wepif.VaultResolver;
 import com.sk89q.worldedit.WorldEdit;
@@ -162,6 +161,7 @@ public class BukkitPlayer extends AbstractPlayerActor {
     public void giveItem(BaseItemStack itemStack) {
         final PlayerInventory inv = player.getInventory();
         ItemStack newItem = BukkitAdapter.adapt(itemStack);
+        TaskManager.taskManager().sync(() -> {
             if (itemStack.getType().getId().equalsIgnoreCase(WorldEdit.getInstance().getConfiguration().wandItem)) {
                 inv.remove(newItem);
             }
@@ -169,9 +169,6 @@ public class BukkitPlayer extends AbstractPlayerActor {
             player.getInventory().setItemInMainHand(newItem);
             HashMap<Integer, ItemStack> overflow = inv.addItem(item);
             if (!overflow.isEmpty()) {
-            TaskManager.taskManager().sync(new RunnableVal<>() {
-                @Override
-                public void run(Object value) {
                 for (Map.Entry<Integer, ItemStack> entry : overflow.entrySet()) {
                     ItemStack stack = entry.getValue();
                     if (stack.getType() != Material.AIR && stack.getAmount() > 0) {
@@ -184,9 +181,9 @@ public class BukkitPlayer extends AbstractPlayerActor {
                     }
                 }
             }
-            });
-        }
             player.updateInventory();
+            return null;
+        });
     }
     //FAWE end
 

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitPlayerBlockBag.java

@@ -20,6 +20,7 @@
 package com.sk89q.worldedit.bukkit;
 
 import com.fastasyncworldedit.core.extent.inventory.SlottableBlockBag;
+import com.fastasyncworldedit.core.util.TaskManager;
 import com.sk89q.worldedit.blocks.BaseItem;
 import com.sk89q.worldedit.blocks.BaseItemStack;
 import com.sk89q.worldedit.extent.inventory.BlockBag;
@@ -171,7 +172,10 @@ public class BukkitPlayerBlockBag extends BlockBag implements SlottableBlockBag
     @Override
     public void flushChanges() {
         if (items != null) {
+            TaskManager.taskManager().sync(() -> {
                 player.getInventory().setContents(items);
+                return null;
+            });
             items = null;
         }
     }

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitWorld.java

@@ -24,6 +24,7 @@ import com.fastasyncworldedit.core.Fawe;
 import com.fastasyncworldedit.core.internal.exception.FaweException;
 import com.fastasyncworldedit.core.queue.IChunkGet;
 import com.fastasyncworldedit.core.queue.implementation.packet.ChunkPacket;
+import com.fastasyncworldedit.core.util.TaskManager;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 import com.sk89q.jnbt.CompoundTag;
@@ -279,12 +280,15 @@ public class BukkitWorld extends AbstractWorld {
             return false;
         }
 
+        TaskManager.taskManager().sync(() -> {
             InventoryHolder chest = (InventoryHolder) state;
             Inventory inven = chest.getInventory();
             if (chest instanceof Chest) {
                 inven = ((Chest) chest).getBlockInventory();
             }
             inven.clear();
+            return null;
+        });
         return true;
     }