express, koa: don't continue past playground render

CHANGELOG.md

@@ -4,6 +4,7 @@ All of the packages in the `apollo-server` repo are released with the same versi
 
 ### vNEXT
 
+- express, koa: remove next after playground [#1436](https://github.com/apollographql/apollo-server/pull/1436)
 - Hapi: Pass the response toolkit to the context function. [#1407](https://github.com/apollographql/apollo-server/pull/1407)
 - update apollo-engine-reporting-protobuf to non-beta [#1429](https://github.com/apollographql/apollo-server/pull/1429)
 

packages/apollo-server-express/src/ApolloServer.ts

@@ -166,7 +166,6 @@ export class ApolloServer extends ApolloServerBase {
           const playground = renderPlaygroundPage(playgroundRenderPageOptions);
           res.write(playground);
           res.end();
-          next();
           return;
         }
       }

packages/apollo-server-koa/src/ApolloServer.ts

@@ -155,7 +155,7 @@ export class ApolloServer extends ApolloServerBase {
               playgroundRenderPageOptions,
             );
             ctx.body = playground;
-            return next();
+            return;
           }
         }
         return graphqlKoa(this.createGraphQLServerOptions.bind(this))(