Prevent dupe bug with recipe command

Essentials/src/main/java/com/earth2me/essentials/commands/Commandrecipe.java

@@ -13,8 +13,10 @@
 import org.bukkit.Material;
 import org.bukkit.NamespacedKey;
 import org.bukkit.Server;
+import org.bukkit.event.inventory.InventoryType;
 import org.bukkit.inventory.FurnaceRecipe;
 import org.bukkit.inventory.InventoryView;
+import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.Recipe;
 import org.bukkit.inventory.RecipeChoice;
@@ -158,7 +160,13 @@ public void shapedRecipe(final CommandSource sender, final ShapedRecipe recipe,
             final User user = ess.getUser(sender.getPlayer());
             user.getBase().closeInventory();
             user.setRecipeSee(true);
-            final InventoryView view = user.getBase().openWorkbench(null, true);
+            final InventoryView view = openWorkbench(user);
+            if (view == null) {
+                user.setRecipeSee(false);
+                return;
+            }
+            final Inventory topInventory = ess.provider(InventoryViewProvider.class).getTopInventory(view);
+
             final String[] recipeShape = recipe.getShape();
             final Map<Character, ItemStack> ingredientMap = recipe.getIngredientMap();
             for (int j = 0; j < recipeShape.length; j++) {
@@ -170,7 +178,7 @@ public void shapedRecipe(final CommandSource sender, final ShapedRecipe recipe,
                     if (VersionUtil.PRE_FLATTENING && item.getDurability() == Short.MAX_VALUE) {
                         item.setDurability((short) 0);
                     }
-                    ess.provider(InventoryViewProvider.class).getTopInventory(view).setItem(j * 3 + k + 1, item);
+                    topInventory.setItem(j * 3 + k + 1, item);
                 }
             }
         } else {
@@ -217,7 +225,11 @@ public void shapelessRecipe(final CommandSource sender, final ShapelessRecipe re
             final User user = ess.getUser(sender.getPlayer());
             user.getBase().closeInventory();
             user.setRecipeSee(true);
-            final InventoryView view = user.getBase().openWorkbench(null, true);
+            final InventoryView view = openWorkbench(user);
+            if (view == null) {
+                user.setRecipeSee(false);
+                return;
+            }
             for (int i = 0; i < ingredients.size(); i++) {
                 final ItemStack item = ingredients.get(i);
                 if (VersionUtil.PRE_FLATTENING && item.getDurability() == Short.MAX_VALUE) {
@@ -239,6 +251,17 @@ public void shapelessRecipe(final CommandSource sender, final ShapelessRecipe re
         }
     }
 
+    private InventoryView openWorkbench(final User user) {
+        final InventoryView view = user.getBase().openWorkbench(null, true);
+        // If InventoryOpenEvent is canceled, the items can end up in the player's own crafting grid
+        // which allows players to extract counterfeit items.
+        if (view == null)
+            return null;
+
+        final Inventory inventory = ess.provider(InventoryViewProvider.class).getTopInventory(view);
+        return inventory.getType() == InventoryType.WORKBENCH ? view : null;
+    }
+
     public String getMaterialName(final CommandSource sender, final ItemStack stack) {
         if (stack == null) {
             return sender.tl("recipeNothing");