SPIGOT-4292: Ignore itemstacks with invalid enchants

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

@@ -299,7 +299,10 @@ public final class CraftItemStack extends ItemStack {
             String id = ((NBTTagCompound) list.get(i)).getString(ENCHANTMENTS_ID.NBT);
             int level = 0xffff & ((NBTTagCompound) list.get(i)).getShort(ENCHANTMENTS_LVL.NBT);
 
-            result.put(Enchantment.getByKey(CraftNamespacedKey.fromString(id)), level);
+            Enchantment enchant = Enchantment.getByKey(CraftNamespacedKey.fromStringOrNull(id));
+            if (enchant != null) {
+                result.put(enchant, level);
+            }
         }
 
         return result.build();

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

@@ -381,7 +381,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable {
             String id = ((NBTTagCompound) ench.get(i)).getString(ENCHANTMENTS_ID.NBT);
             int level = 0xffff & ((NBTTagCompound) ench.get(i)).getShort(ENCHANTMENTS_LVL.NBT);
 
-            Enchantment enchant = Enchantment.getByKey(CraftNamespacedKey.fromString(id));
+            Enchantment enchant = Enchantment.getByKey(CraftNamespacedKey.fromStringOrNull(id));
             if (enchant != null) {
                 enchantments.put(enchant, level);
             }

src/main/java/org/bukkit/craftbukkit/util/CraftNamespacedKey.java

@@ -8,6 +8,11 @@ public final class CraftNamespacedKey {
     public CraftNamespacedKey() {
     }
 
+    public static NamespacedKey fromStringOrNull(String string) {
+        MinecraftKey minecraft = MinecraftKey.a(string);
+        return (minecraft == null) ? null : fromMinecraft(minecraft);
+    }
+
     public static NamespacedKey fromString(String string) {
         return fromMinecraft(new MinecraftKey(string));
     }