Improve Type::getNamedType return type

Only when null is passed, it will return null.

Otherwise it will always be Type&NamedType.

Author: ruudk

docs/class-reference.md

@@ -270,6 +270,8 @@ static function isInputType($type): bool
  *
  * @return (Type&NamedType)|null
  *
+ * @phpstan-return ($type is null ? null : Type&NamedType)
+ *
  * @api
  */
 static function getNamedType(?GraphQL\Type\Definition\Type $type): ?GraphQL\Type\Definition\Type

src/Type/Definition/QueryPlan.php

@@ -133,7 +133,6 @@ private function analyzeQueryPlan(ObjectType $parentType, iterable $fieldNodes):
             $type = Type::getNamedType(
                 $parentType->getField($fieldNode->name->value)->getType()
             );
-            assert($type instanceof Type, 'known because schema validation');
 
             $subfields = $this->analyzeSelectionSet($fieldNode->selectionSet, $type, $implementors);
             $queryPlan = $this->arrayMergeDeep($queryPlan, $subfields);

src/Type/Definition/Type.php

@@ -192,6 +192,8 @@ public static function isInputType($type): bool
      *
      * @return (Type&NamedType)|null
      *
+     * @phpstan-return ($type is null ? null : Type&NamedType)
+     *
      * @api
      */
     public static function getNamedType(?Type $type): ?Type

src/Type/SchemaValidationContext.php

@@ -835,7 +835,6 @@ private function validateTypeIsSingleton(Type $type, string $path): void
         }
 
         $namedType = Type::getNamedType($type);
-        assert($namedType !== null, 'because getNamedType() was called with non-null type');
         if ($namedType->isBuiltInType()) {
             return;
         }