Make FieldItemListPropertyReflection entity property nullable

src/Reflection/FieldItemListPropertyReflection.php

@@ -9,6 +9,7 @@
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
+use PHPStan\Type\UnionType;
 use function in_array;
 
 /**
@@ -42,7 +43,7 @@ public static function canHandleProperty(ClassReflection $classReflection, strin
     public function getReadableType(): Type
     {
         if ($this->propertyName === 'entity') {
-            return new ObjectType('Drupal\Core\Entity\EntityInterface');
+            return new UnionType([new ObjectType('Drupal\Core\Entity\EntityInterface'), new NullType()]);
         }
         if ($this->propertyName === 'target_id') {
             // @todo needs to be union type.
@@ -60,7 +61,7 @@ public function getReadableType(): Type
     public function getWritableType(): Type
     {
         if ($this->propertyName === 'entity') {
-            return new ObjectType('Drupal\Core\Entity\EntityInterface');
+            return new UnionType([new ObjectType('Drupal\Core\Entity\EntityInterface'), new NullType()]);
         }
         if ($this->propertyName === 'target_id') {
             return new StringType();

tests/src/Reflection/EntityFieldsViaMagicReflectionExtensionTest.php

@@ -13,6 +13,7 @@
 use PHPStan\Type\NullType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\StringType;
+use PHPStan\Type\VerbosityLevel;
 
 final class EntityFieldsViaMagicReflectionExtensionTest extends PHPStanTestCase {
 
@@ -119,7 +120,7 @@ public function testGetPropertyFieldItemList(): void
         self::assertInstanceOf(StringType::class, $readableType);
         $propertyReflection = $this->extension->getProperty($classReflection, 'entity');
         $readableType = $propertyReflection->getReadableType();
-        self::assertInstanceOf(ObjectType::class, $readableType);
+        self::assertSame('Drupal\Core\Entity\EntityInterface|null', $readableType->describe(VerbosityLevel::typeOnly()));
         $propertyReflection = $this->extension->getProperty($classReflection, 'format');
         $readableType = $propertyReflection->getReadableType();
         self::assertInstanceOf(NullType::class, $readableType);