await appoloServer to stop, before starting a new one

Author: arash16

src/service.js

@@ -607,14 +607,14 @@ module.exports = function (mixinOptions) {
 			/**
 			 * Prepare GraphQL schemas based on Moleculer services.
 			 */
-			prepareGraphQLSchema() {
+			async prepareGraphQLSchema() {
 				// Schema is up-to-date
 				if (!this.shouldUpdateGraphqlSchema && this.graphqlHandler) {
 					return;
 				}
-				
+
 				if (this.apolloServer) {
-					this.apolloServer.stop();
+					await this.apolloServer.stop();
 				}
 
 				// Create new server & regenerate GraphQL schema
@@ -734,17 +734,17 @@ module.exports = function (mixinOptions) {
 
 			const route = _.defaultsDeep(mixinOptions.routeOptions, {
 				aliases: {
-					"/"(req, res) {
+					async "/"(req, res) {
 						try {
-							this.prepareGraphQLSchema();
+							await this.prepareGraphQLSchema();
 							return this.graphqlHandler(req, res);
 						} catch (err) {
 							this.sendError(req, res, err);
 						}
 					},
-					"GET /.well-known/apollo/server-health"(req, res) {
+					async "GET /.well-known/apollo/server-health"(req, res) {
 						try {
-							this.prepareGraphQLSchema();
+							await this.prepareGraphQLSchema();
 						} catch (err) {
 							res.statusCode = 503;
 							return this.sendResponse(
@@ -783,8 +783,8 @@ module.exports = function (mixinOptions) {
 					query: { type: "string" },
 					variables: { type: "object", optional: true },
 				},
-				handler(ctx) {
-					this.prepareGraphQLSchema();
+				async handler(ctx) {
+					await this.prepareGraphQLSchema();
 					return GraphQL.graphql(
 						this.graphqlSchema,
 						ctx.params.query,