Errors do not bubble up to `formatError`

[timrs2998]

Summary

I'm creating an issue here so you're aware, but I ultimately believe this is an issue with graphql-tools. When throwing a GrampsError, graphql-tools removes all properties except error.message and rethrows a new error. As a result, the formatError provided by the @gramps/errors package is useless.

Walkthrough

When a GrampsError is thrown, it is caught by graphql-tools stitching logic and rethrown:

https://github.com/apollographql/graphql-tools/blob/master/src/stitching/errors.ts#L84

    const errorMessage = result.errors
      .map((error: { message: string }) => error.message)
      .join('\n');
    throw locatedError(
      new Error(errorMessage),
      ..,
      ..,
    );

Later, the new error bubbles up to the formatError logic from @gramps/errors:

import { formatError } from '@gramps/errors'

app.use(graphqlExpress({ formatError })

However, the formatError function does not receive the expected GrampsErrors, rather, it receives a different error object transformed and rethrown by graphql-tools. It cannot log the targetEndpoint, statusCode, docsLink, and other fields on a GrampsError because the error has been caught and rethrown by graphql-tools.

I can write a short gist to reproduce it if you want.

[timrs2998]

possibly related:

• Stitching with formatError is very limited... ardatan/graphql-tools#480
• Maintain original errors through stitching ardatan/graphql-tools#485

[jlengstorf]

I noticed this and haven't had the time to dig into it, unfortunately. 😢

I'm putting together a roadmap for Q1 that includes figuring out why this stopped working and either patching it or looking for the root cause in graphql-tools, if it's there. If someone else has time before I get to it, that would be very much appreciated.

[timrs2998]

As a workaround, we've decided on a hack solution of serializing JSON into the error message string, and deserializing later in formatError

[timrs2998]

ardatan/graphql-tools#637

[ryanomackey]

Yeah, this seems like a valid workaround:

In your data source model:

  handleError(response) {
      const serialized = JSON.stringify(GrampsError({
        statusCode: response.statusCode,
        description: response.error.message,
        errorCode: response.error.code,
        targetEndpoint: response.options.uri,
        graphqlModel: this.constructor.name
      }));

      throw Error(serialized);
  }

And when you need to call formatError:

gramps({
  ...
  apollo: {
    graphqlExpress: {
      formatError: formatError(logger)(JSON.parse(err.message)),
    },
  },
});

Less than ideal, for sure.