fix(utils): support old TypeScript versions

Author: ardatan

.changeset/old-forks-think.md

@@ -0,0 +1,5 @@
+---
+'@graphql-tools/utils': patch
+---
+
+fix(utils): support old TypeScript versions

packages/utils/src/AggregateError.ts

@@ -1,5 +1,15 @@
-/// <reference lib="es2021.promise" />
-let AggregateErrorImpl = globalThis.AggregateError;
+// Backwards compability for old versions of TypeScript
+interface AggregateError extends Error {
+  errors: any[];
+}
+
+interface AggregateErrorConstructor {
+  new (errors: Iterable<any>, message?: string): AggregateError;
+  (errors: Iterable<any>, message?: string): AggregateError;
+  readonly prototype: AggregateError;
+}
+
+let AggregateErrorImpl: AggregateErrorConstructor = globalThis.AggregateError;
 
 if (typeof AggregateErrorImpl === 'undefined') {
   class AggregateErrorClass extends Error implements AggregateError {