Item: Remove "ench" tag when all enchantments are removed from an item (#4184)

fixes #4144

src/pocketmine/item/Item.php

@@ -339,7 +339,11 @@ class Item implements ItemIds, \JsonSerializable{
 			}
 		}
 
+		if($ench->getCount() > 0){
 			$this->setNamedTagEntry($ench);
+		}else{
+			$this->removeNamedTagEntry(self::TAG_ENCH);
+		}
 	}
 
 	public function removeEnchantments() : void{

tests/phpstan/configs/l8-baseline.neon

@@ -1605,6 +1605,11 @@ parameters:
 			count: 1
 			path: ../../../src/pocketmine/utils/Utils.php
 
+		-
+			message: "#^Parameter \\#1 \\$enchantment of class pocketmine\\\\item\\\\enchantment\\\\EnchantmentInstance constructor expects pocketmine\\\\item\\\\enchantment\\\\Enchantment, pocketmine\\\\item\\\\enchantment\\\\Enchantment\\|null given\\.$#"
+			count: 1
+			path: ../../phpunit/item/ItemTest.php
+
 		-
 			message: "#^Cannot call method cancel\\(\\) on pocketmine\\\\scheduler\\\\TaskHandler\\|null\\.$#"
 			count: 1

tests/phpunit/item/ItemTest.php

@@ -25,12 +25,15 @@ namespace pocketmine\item;
 
 use PHPUnit\Framework\TestCase;
 use pocketmine\block\BlockFactory;
+use pocketmine\item\enchantment\Enchantment;
+use pocketmine\item\enchantment\EnchantmentInstance;
 
 class ItemTest extends TestCase{
 
 	public function setUp() : void{
 		BlockFactory::init();
 		ItemFactory::init();
+		Enchantment::init();
 	}
 
 	/**
@@ -61,6 +64,16 @@ class ItemTest extends TestCase{
 		}
 	}
 
+	/**
+	 * Tests that when all enchantments are removed from an item, the "ench" tag is removed as well
+	 */
+	public function testEnchantmentRemoval() : void{
+		$item = ItemFactory::get(Item::DIAMOND_SWORD);
+		$item->addEnchantment(new EnchantmentInstance(Enchantment::getEnchantment(Enchantment::SHARPNESS)));
+		$item->removeEnchantment(Enchantment::SHARPNESS);
+		self::assertNull($item->getNamedTag()->getTag(Item::TAG_ENCH));
+	}
+
 	/**
 	 * @return mixed[][]
 	 * @phpstan-return list<array{string,int,int}>