Data is getting set null when errors come from stitched remote schemas

[suwigyarathore]

Discussed in #4056

^{Originally posted by guifeliper December 27, 2021}

Setup:

We have the following code for stitching the remote schemas; they are perfectly working.

const makeGatewaySchema = async () => {
  return stitchSchemas({
      subschemas: [
        {
          schema: await introspectSchema(remoteExecutorA, baseContext),
          executor: remoteExecutorA,
        },
        {
          schema: await introspectSchema(remoteExecutorB, baseContext),
          executor: remoteExecutorB,
        },
      ],
    }):
 }


const runServer = async () => {
  const schema = await makeGatewaySchema();
  const app = express();
  app.use(
    '/',
    graphqlHTTP(() => ({
      schema,
      graphiql: true,
    }))
  );

  let { PORT } = process.env;
  PORT = PORT || '3333';
  app.listen(PORT, () => {
    console.log(`Listening on http://localhost:${PORT}`);
  });
};

https://www.graphql-tools.com/docs/remote-schemas

Scenario 1:

The response from one of the stitched graphql endpoint has error and data, the data on the client-side is returned as null, and the error has its message aggregated. However, a simple console.log on remote executor shows us that we have data and more than one error coming from the underlying subschema. Here is the current response on the client-side:

{
   "errors":[
      {
         "message":"Account <###@###.com> not found, \nAccount <###@###.com> not found",
         "path":[
            "organization"
         ]
      }
   ],
   "data":{
      "organization":null
   }
}

The following response shows us what we receive from the remote executor.

{
   "errors":[
      {
         "message":"Account <###@###.com> not found",
         "path":[
            "Array"
         ],
         "extensions":[
            "Object"
         ]
      },
      {
         "message":"Account <###@###.com>  not found",
         "path":[
            "Array"
         ],
         "extensions":[
            "Object"
         ]
      }
   ],
   "data":{
      "__typename":"Query",
      "organization":{
         "accounts":[
            "Array"
         ],
         "__typename":"Organization"
      }
   }
}

Scenario 2:

The query has errors and no data. The response on the client-side receives a 500 network error. The following response shows us what we receive from the remote executor.

{
   "errors":[
      {
         "message":"Account <###@###.com> not found",
         "path":[
            "Array"
         ],
         "extensions":[
            "Object"
         ]
      },
      {
         "message":"Account <###@###.com>  not found",
         "path":[
            "Array"
         ],
         "extensions":[
            "Object"
         ]
      }
   ],
   "data": null
   }
}

Expectations

The data and error should be preserved as it is and should be passed to the client unmodified.