SPIGOT-1610: Treat clicking on an inventory window as clicking outside it

src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryView.java

@@ -125,7 +125,7 @@ public class CraftInventoryView extends InventoryView {
                 // Nothing to do, it's a CONTAINER slot
             }
         } else {
-            if (slot == -999) {
+            if (slot == -999 || slot == -1) {
                 type = SlotType.OUTSIDE;
             } else if (inventory.getType() == InventoryType.CRAFTING) {
                 if (slot < 9) {