Fixed World Unload Crash.

Fixed render crashes for items that are not available.
Parts now load properly.

client/render/BusRenderer.java

@@ -32,6 +32,7 @@ public class BusRenderer implements IItemRenderer
 		if ( part == null )
 		{
 			part = c.createPartFromItemStack( is );
+			if ( part != null )
 				renderPart.put( id, part );
 		}
 
@@ -53,6 +54,9 @@ public class BusRenderer implements IItemRenderer
 	@Override
 	public void renderItem(ItemRenderType type, ItemStack item, Object... data)
 	{
+		if ( item == null )
+			return;
+
 		GL11.glPushMatrix();
 		if ( type == ItemRenderType.ENTITY )
 			GL11.glTranslatef( -0.5f, -0.5f, -0.5f );
@@ -83,7 +87,11 @@ public class BusRenderer implements IItemRenderer
 				fp.renderInventory( BusRenderHelper.instance, renderer );
 		}
 		else
-			getRenderer( item, (IPartItem) item.getItem() ).renderInventory( BusRenderHelper.instance, renderer );
+		{
+			IPart ip = getRenderer( item, (IPartItem) item.getItem() );
+			if ( ip != null )
+				ip.renderInventory( BusRenderHelper.instance, renderer );
+		}
 
 		GL11.glPopMatrix();
 	}

core/CreativeTab.java

@@ -1,8 +1,10 @@
 package appeng.core;
 
+import net.minecraft.block.Block;
 import net.minecraft.creativetab.CreativeTabs;
 import net.minecraft.item.ItemStack;
 import appeng.api.AEApi;
+import appeng.api.util.AEItemDefinition;
 import appeng.util.Platform;
 
 public final class CreativeTab extends CreativeTabs
@@ -19,7 +21,21 @@ public final class CreativeTab extends CreativeTabs
 	@Override
 	public ItemStack getIconItemStack()
 	{
-		return AEApi.instance().items().itemWirelessTerminal.stack( 1 );
+		return findFirst( AEApi.instance().blocks().blockController, AEApi.instance().blocks().blockChest, AEApi.instance().blocks().blockCellWorkbench,
+				AEApi.instance().blocks().blockFluix, AEApi.instance().items().itemCell1k, AEApi.instance().items().itemNetworkTool,
+				AEApi.instance().materials().materialFluixCrystal, AEApi.instance().materials().materialCertusQuartzCrystal );
+	}
+
+	private ItemStack findFirst(AEItemDefinition... choices)
+	{
+		for (AEItemDefinition a : choices)
+		{
+			ItemStack is = a.stack( 1 );
+			if ( is != null )
+				return is;
+		}
+
+		return new ItemStack( Block.chest );
 	}
 
 	public static void init()

helpers/TickHandler.java

@@ -83,17 +83,21 @@ public class TickHandler implements ITickHandler
 	{
 		if ( Platform.isServer() )
 		{
-			while (!getRepo().networks.isEmpty())
+			LinkedList<IGridNode> toDestroy = new LinkedList();
+
+			for (Grid g : getRepo().networks)
 			{
-				Grid g = getRepo().networks.poll();
 				for (IGridNode n : g.getNodes())
 				{
 					if ( n.getWorld() == ev.world )
+						toDestroy.add( n );
+				}
+			}
+
+			for (IGridNode n : toDestroy)
 				n.destroy();
 		}
 	}
-		}
-	}
 
 	@Override
 	public void tickStart(EnumSet<TickType> type, Object... tickData)

items/parts/ItemPart.java

@@ -51,8 +51,7 @@ public class ItemPart extends AEBaseItem implements IPartItem, IItemGroup
 		try
 		{
 			ItemStack is = new ItemStack( this );
-			PartType t = getTypeByStack( is );
-			t.getPart().getConstructor( ItemStack.class ).newInstance( is );
+			mat.getPart().getConstructor( ItemStack.class ).newInstance( is );
 		}
 		catch (Throwable e)
 		{
@@ -92,7 +91,14 @@ public class ItemPart extends AEBaseItem implements IPartItem, IItemGroup
 
 	public PartType getTypeByStack(ItemStack is)
 	{
-		return dmgToPart.get( is.getItemDamage() ).part;
+		if ( is == null )
+			return null;
+
+		PartTypeIst pt = dmgToPart.get( is.getItemDamage() );
+		if ( pt != null )
+			return pt.part;
+
+		return null;
 	}
 
 	@Override
@@ -123,7 +129,11 @@ public class ItemPart extends AEBaseItem implements IPartItem, IItemGroup
 	@Override
 	public String getItemDisplayName(ItemStack is)
 	{
-		Enum[] varients = getTypeByStack( is ).getVarients();
+		PartType pt = getTypeByStack( is );
+		if ( pt == null )
+			return "Unnamed";
+
+		Enum[] varients = pt.getVarients();
 
 		if ( varients != null )
 			return super.getItemDisplayName( is ) + " - " + varients[dmgToPart.get( is.getItemDamage() ).varient].toString();
@@ -153,6 +163,7 @@ public class ItemPart extends AEBaseItem implements IPartItem, IItemGroup
 		try
 		{
 			PartType t = getTypeByStack( is );
+			if ( t != null )
 				return t.getPart().getConstructor( ItemStack.class ).newInstance( is );
 		}
 		catch (Throwable e)
@@ -160,6 +171,7 @@ public class ItemPart extends AEBaseItem implements IPartItem, IItemGroup
 			throw new RuntimeException( "Unable to construct IBusPart from IBusItem : " + getTypeByStack( is ).getPart().getName()
 					+ " ; Possibly didn't have correct constructor( ItemStack )", e );
 		}
+		return null;
 	}
 
 	@Override