Cannot write file because it awaits indefinitely
I'm following Apollo's [tutorial ](https://www.apollographql.com/blog/graphql/file-uploads/with-react-hooks-typescript-amazon-s3-tutorial/) on integrating graphql-upload, except I'm using Angular as my front end. I have `apollo-angular` and `apollo-upload-client` installed on my front-end, and `graphql-upload` installed on my backend.

I'm able to receive the file, however I cannot write the file anywhere. My resolver ends up awaiting indefinitely. Here's my resolver code:
```typescript
export default {
  Mutation: {
    updateUser: async (parent, args, context: ApolloResolversContext, info) => {
      if (args.input) {
        const { createReadStream, filename, mimetype, encoding } = await <FileUpload>args.input;

        console.log('file uploading...');

        // Invoking the `createReadStream` will return a Readable Stream.
        // See https://nodejs.org/api/stream.html#stream_readable_streams
        const stream = createReadStream();

        // This is purely for demonstration purposes and will overwrite the
        // local-file-output.txt in the current working directory on EACH upload.
        const out = fs.createWriteStream(`uploads/${filename}`);
        stream.pipe(out);
        await finished(out);

        console.log('file uploaded!');
      }
      
      return true;
    }
  }
} as { Query: QueryResolvers, Mutation: MutationResolvers };
```

Due to dependency issues, I'm also using `graphql v15.8.0`, which means I'm relying on an older version of graphql-upload (`v13.0.0`).