Aliased fields always null when `mergeSchemas` and `stitchSchemas` combined.

[jacobkatz-tamg]

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• [ ] 1. The issue provides a reproduction available on Github, Stackblitz or CodeSandbox

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  Please make sure the GraphQL Tools package versions under package.json matches yours.

• [ ] 2. A failing test has been provided
• [ ] 3. A local solution has been provided
• [ ] 4. A pull request is pending review

---

Describe the bug

Queries with aliases fail when @graphql-tools/schema's mergeSchemas is used to merge a schema produced by @graphql-tools/stitch's stitchSchemas

To Reproduce Steps to reproduce the behavior:

For example, here is a test that fails today:

import { graphql } from 'graphql';

import { makeExecutableSchema } from '@graphql-tools/schema';
import { mergeSchemas } from '@graphql-tools/schema';
import { stitchSchemas } from '@graphql-tools/stitch';
import { assertSome } from '@graphql-tools/utils';

describe('aliasing', () => {
  test('works', async () => {
    let chirpSchema = makeExecutableSchema({
      typeDefs: /* GraphQL */ `
        type Chirp {
          id: ID!
          text: String
        }

        type Query {
          chirpById(id: ID!): Chirp
        }
      `,
      resolvers: {
        Query: {
          chirpById: (_obj, args ) =>
            args.id % 3 === 0 ? null : {
              id: args.id,
              text: 'chirp ' + args.id
            }
          },
        },
    })
    let dummySchema = makeExecutableSchema({
      typeDefs: /* GraphQL */ `
        type Query {
          dummy: String
        }
      `,
      resolvers: {
        Query: {
          dummy: () => null
        },
      }
    })

    const mergedSchema = mergeSchemas({
      schemas: [stitchSchemas({subschemas: [chirpSchema, dummySchema]})],
    });

    const query = /* GraphQL */ `
      query {
        thisBreaks: chirpById(id: 2) {
          id
          textAlias: text
        }
        working: chirpById(id: 2) {
          id
          text
        }
        alsoWorking: chirpById(id: 2) {
          id
          text
          textAlias: text
        }
      }
    `;

    const result = await graphql({ schema: mergedSchema, source: query });

    expect(result.errors).toBeUndefined();
    assertSome(result.data);
    const working: any = result.data['working'];
    expect(working.id).not.toBe(null);
    expect(working.id).toBe('2');
    expect(working.text).toBe('chirp 2');

    const alsoWorking: any = result.data['alsoWorking'];
    expect(alsoWorking.id).not.toBe(null);
    expect(alsoWorking.id).toBe('2');
    expect(alsoWorking.text).toBe('chirp 2');
    expect(alsoWorking.textAlias).toBe('chirp 2');

    const thisBreaks: any = result.data['thisBreaks'];
    expect(thisBreaks.id).not.toBe(null);
    expect(thisBreaks.id).toBe('2');
    // it breaks right here - this field is null and should not be.
    expect(thisBreaks.textAlias).toBe('chirp 2');
  });
});

Expected behavior

One would expect that if

query {
  chirpById(id: 2) {
    text
  }
}

resolves to { chirpById: { text: "chirp 2" } },

query {
  chirpById(id: 2) {
    textAlias: text
  }
}

would resolve to { chirpById: { textAlias: "chirp 2" } }, but instead it resolves to { chirpById: { textAlias: null } }

Environment:

• OS: amazon linux, osx, etc
• @graphql-tools/...:
• NodeJS:

Additional context

I have not been able to reproduce with just mergeSchemas or just stitchSchemas.