Fix type for customFormatErrorFn

[hokaccha]

customFormatErrorFn may be passed HttpError as well as GraphQLError. So the argument type of customFormatErrorFn should be GraphQLError | HttpError.

Example

import { graphqlHTTP } from "express-graphql";
import express from "express";
import { buildSchema, formatError, GraphQLError, GraphQLFormattedError } from "graphql";
import { HttpError } from "http-errors";

const app = express();

const schema = buildSchema(`
  type Query {
    hello: String
  }
`);

app.use(
  "/graphql",
  graphqlHTTP(() => {
    return {
      schema,
      customFormatErrorFn: (err: GraphQLError): GraphQLFormattedError => {
        (err as any).extensions = {
          name: err.name,
          isHttpError: err instanceof HttpError,
        };
        return formatError(err);
      },
    };
  })
);

app.listen(8000);

$ curl -s -X POST http://localhost:8000/graphql | jq
{
  "errors": [
    {
      "message": "Must provide query string.",
      "extensions": {
        "name": "BadRequestError",
        "isHttpError": true
      }
    }
  ]
}

[IvanGoncharov]

@hokaccha Thanks for the detailed report 👍
I change code to always wrap HTTP errors in GraphQLError in #716

[hokaccha]

Thanks!