fix bug

src/main/java/com/glodblock/github/common/tile/TileLevelMaintainer.java

@@ -82,8 +82,12 @@ public class TileLevelMaintainer extends AENetworkTile
                                 .getStorage()
                                 .getFluidInventory()
                                 .injectItems(ItemFluidDrop.getAeFluidStack(items), mode, this.source);
-                        items.setStackSize(notInserted.getStackSize());
-                        return items;
+                        if (notInserted != null) {
+                            items.setStackSize(notInserted.getStackSize());
+                            return items;
+                        } else {
+                            return null;
+                        }
                     } else {
                         return this.getProxy().getStorage().getItemInventory().injectItems(items, mode, this.source);
                     }

src/main/java/com/glodblock/github/crossmod/waila/WailaInit.java

@@ -2,6 +2,7 @@ package com.glodblock.github.crossmod.waila;
 
 import appeng.api.parts.IPartHost;
 import appeng.tile.AEBaseTile;
+import appeng.util.Platform;
 import codechicken.nei.guihook.GuiContainerManager;
 import cpw.mods.fml.common.event.FMLInterModComms;
 import mcp.mobius.waila.api.IWailaDataProvider;
@@ -17,7 +18,7 @@ public class WailaInit {
         final IWailaDataProvider part = new PartWailaDataProvider();
         registrar.registerBodyProvider(part, IPartHost.class);
         registrar.registerNBTProvider(part, IPartHost.class);
-        GuiContainerManager.addTooltipHandler(new FCTooltipHandlerWaila());
+        if (Platform.isClient()) GuiContainerManager.addTooltipHandler(new FCTooltipHandlerWaila());
 
         final IWailaDataProvider tile = new TileWailaDataProvider();
         registrar.registerBodyProvider(tile, AEBaseTile.class);