Fix NPE in item panel getMask (#1078)

src/main/java/codechicken/nei/ItemPanel.java

@@ -75,13 +75,7 @@ public class ItemPanel extends PanelWidget<ItemsPanelGrid> {
     }
 
     public static void updateItemList(ArrayList<ItemStack> newItems) {
-        final ItemsPanelGrid grid = ItemPanels.itemPanel.getGrid();
-
-        if (grid.rawItems.size() != newItems.size()) {
-            grid.setPage(0);
-        }
-
-        grid.setItems(newItems);
+        ItemPanels.itemPanel.getGrid().setItems(newItems);
         ItemPanels.itemPanel.realItems = newItems;
     }
 

src/main/java/codechicken/nei/ItemsPanelGrid.java

@@ -89,6 +89,10 @@ public class ItemsPanelGrid extends ItemsGrid<ItemsPanelGrid.ItemsPanelGridSlot,
     public void refresh(GuiContainer gui) {
 
         if (this.newItems != null) {
+            if (this.rawItems.size() != this.newItems.size()) {
+                this.page = 0;
+            }
+
             this.groupItems.clear();
             this.itemToGroup.clear();
             this.forceExpand = false;