add try/catch and test for rejected options

src/integrations/expressApollo.ts

@@ -31,7 +31,12 @@ export function graphqlHTTP(options: ApolloOptions | ExpressApolloOptionsFunctio
   return async (req: express.Request, res: express.Response, next) => {
     let optionsObject: ApolloOptions;
     if (isOptionsFunction(options)) {
+      try {
         optionsObject = await options(req);
+      } catch (e) {
+        res.status(500);
+        res.send(`Invalid options provided to ApolloServer: ${e.message}`);
+      }
     } else {
       optionsObject = options;
     }

src/integrations/integrations.test.ts

@@ -102,6 +102,22 @@ export default (createApp: CreateAppFunc) => {
           });
       });
 
+      it('throws an error if options promise is rejected', () => {
+          const app = createApp({ apolloOptions: () => {
+            return Promise.reject({}) as any as ApolloOptions
+          }});
+          const expected = 'Invalid options';
+          const req = request(app)
+              .post('/graphql')
+              .send({
+                  query: 'query test{ testString }',
+              });
+          return req.then((res) => {
+              expect(res.status).to.equal(500);
+              return expect(res.error.text).to.contain(expected);
+          });
+      });
+
       it('throws an error if POST body is missing', () => {
           const app = createApp({excludeParser: true});
           const req = request(app)