Fix error when visiting __type fields (#5016)

* Add test case

* Fix error when visiting __type fields

* Add changeset

Author: mayrn-techdivision

.changeset/fluffy-masks-develop.md

@@ -0,0 +1,5 @@
+---
+'@graphql-tools/utils': patch
+---
+
+Fixes introspection query issues when visiting field '\_\_type'

packages/utils/src/visitResult.ts

@@ -11,6 +11,7 @@ import {
   isObjectType,
   OperationDefinitionNode,
   GraphQLError,
+  TypeMetaFieldDef,
   TypeNameMetaFieldDef,
   FragmentDefinitionNode,
   SchemaMetaFieldDef,
@@ -240,6 +241,9 @@ function visitObjectValue(
         case '__schema':
           fieldType = SchemaMetaFieldDef.type;
           break;
+        case '__type':
+          fieldType = TypeMetaFieldDef.type;
+          break;
       }
     }
 

packages/utils/tests/visitResult.test.ts

@@ -58,6 +58,22 @@ describe('visiting results', () => {
     expect(() => visitResult(result, introspectionRequest, schema, undefined)).not.toThrow();
   });
 
+  it('should visit with type query and visitor map without throwing', async () => {
+    const introspectionRequest: ExecutionRequest = {
+      document: parse('{ __type(name: "Test") { __typename name } }'),
+      variables: {},
+    };
+
+    const result = {
+      data: {
+        __type: {
+          __typename: '__Type',
+        },
+      },
+    };
+    expect(() => visitResult(result, introspectionRequest, schema, {})).not.toThrow();
+  });
+
   it('should visit with a request with introspection fields without throwing', async () => {
     const introspectionRequest: ExecutionRequest = {
       document: parse(getIntrospectionQuery()),