Fix type overrides of GQL service getSchema

api/src/services/graphql.ts

@@ -28,6 +28,7 @@ import {
 	GraphQLError,
 	GraphQLNonNull,
 	FragmentDefinitionNode,
+	GraphQLSchema,
 } from 'graphql';
 import { getGraphQLType } from '../utils/get-graphql-type';
 import { RelationsService } from './relations';
@@ -142,6 +143,9 @@ export class GraphQLService {
 	/**
 	 * Generate the GraphQL schema. Pulls from the schema information generated by the get-schema util.
 	 */
+	getSchema(): GraphQLSchema;
+	getSchema(type: 'schema'): GraphQLSchema;
+	getSchema(type: 'sdl'): string;
 	getSchema(type: 'schema' | 'sdl' = 'schema') {
 		const self = this;