Fixed a couple of things.

Hopefully all works now. >_>

src/main/java/de/ellpeck/actuallyadditions/mod/blocks/BlockGiantChest.java

@@ -76,10 +76,13 @@ public class BlockGiantChest extends BlockContainerBase{
                 ItemStack[] slots = ((TileEntityGiantChest)tile).slots;
 
                 for(int i = 0; i < list.tagCount(); i++){
+                    NBTTagCompound compound = list.getCompoundTagAt(i);
+                    if(compound != null && compound.hasKey("id")){
                         slots[i] = ItemStack.loadItemStackFromNBT(list.getCompoundTagAt(i));
                     }
                 }
             }
+        }
 
         super.onBlockPlacedBy(world, pos, state, entity, stack);
     }

src/main/java/de/ellpeck/actuallyadditions/mod/data/WorldData.java

@@ -48,11 +48,17 @@ public class WorldData{
         int dim = world.provider.getDimension();
         WorldData data = worldData.get(dim);
 
-        if(data == null && world.isRemote){
+        if(data == null){
             data = new WorldData(null, dim);
+
+            if(world.isRemote){
                 worldData.put(dim, data);
                 ModUtil.LOGGER.info("Creating temporary WorldData for world "+dim+" on the client!");
             }
+            else{
+                ModUtil.LOGGER.warn("Trying to get WorldData from world "+dim+" that doesn't have any data!? This shouldn't happen!");
+            }
+        }
 
         return data;
     }

src/main/java/de/ellpeck/actuallyadditions/mod/tile/TileEntityInventoryBase.java

@@ -59,6 +59,7 @@ public abstract class TileEntityInventoryBase extends TileEntityBase implements
             NBTTagList tagList = compound.getTagList("Items", 10);
             for(int i = 0; i < tagList.tagCount(); i++){
                 NBTTagCompound tagCompound = tagList.getCompoundTagAt(i);
+                if(tagCompound != null && tagCompound.hasKey("id")){
                     byte slotIndex = tagCompound.getByte("Slot");
                     if(slotIndex >= 0 && slotIndex < slots.length){
                         slots[slotIndex] = ItemStack.loadItemStackFromNBT(tagCompound);
@@ -66,6 +67,7 @@ public abstract class TileEntityInventoryBase extends TileEntityBase implements
                 }
             }
         }
+    }
 
     public void initializeSlots(int itemAmount){
         this.slots = new ItemStack[itemAmount];

src/main/java/de/ellpeck/actuallyadditions/mod/util/WorldUtil.java

@@ -340,8 +340,16 @@ public class WorldUtil{
      * @return If the Block could be harvested normally (so that it drops an item)
      */
     public static boolean playerHarvestBlock(World world, BlockPos pos, EntityPlayer player){
-        Block block = PosUtil.getBlock(pos, world);
         IBlockState state = world.getBlockState(pos);
+        if(state == null){
+            return false;
+        }
+
+        Block block = state.getBlock();
+        if(block == null){
+            return false;
+        }
+
         TileEntity tile = world.getTileEntity(pos);
         ItemStack stack = player.getHeldItemMainhand();
 
@@ -351,7 +359,8 @@ public class WorldUtil{
         //Send Block Breaking Event
         int xp = -1;
         if(player instanceof EntityPlayerMP){
-            xp = ForgeHooks.onBlockBreakEvent(world, ((EntityPlayerMP)player).interactionManager.getGameType(), (EntityPlayerMP)player, pos);
+            EntityPlayerMP playerMP = (EntityPlayerMP)player;
+            xp = ForgeHooks.onBlockBreakEvent(world, playerMP.interactionManager.getGameType(), playerMP, pos);
             if(xp == -1){
                 return false;
             }
@@ -397,6 +406,7 @@ public class WorldUtil{
             //Check the Server if a Block that changed on the Client really changed, if not, revert the change
             Minecraft.getMinecraft().getConnection().sendPacket(new CPacketPlayerDigging(CPacketPlayerDigging.Action.STOP_DESTROY_BLOCK, pos, Minecraft.getMinecraft().objectMouseOver.sideHit));
         }
+
         return removed;
     }
 }