backstage: Techdocs can't query catalog metadata when using app-backend

When using app-backend where frontend and backend are running off the same URL, Techdocs is not able to retrieve metadata and fails.

Expected Behavior

Should be able to use Techdocs in app-backend.

Current Behavior

For some reason, fetch to ${catalogUrl}/entities/by-name/${kind}/${namespace}/${name} returns content of index.html instead of metadata. I can use the generated URL to retrieve the metadata by calling the API directly via the browser.

Possible Solution

🤷‍♀️

Steps to Reproduce

1. Using release 0.2.0

app:
  baseUrl: http://localhost:7000

backend:
  baseUrl: http://localhost:7000
  listen:
    port: 7000
  csp:
    connect-src: ["'self'", 'http:', 'https:']

techdocs:
  storageUrl: http://localhost:7000/api/techdocs/static/docs
  requestUrl: http://localhost:7000/api/techdocs

1. Use the config above on the example app and backend
2. Try to generate documentation
3. You should get a similar error as above

Context

Trying to get a basic documentation site working for demo purposes.

Your Environment

• NodeJS Version (v12): 12
• Operating System and Version (e.g. Ubuntu 14.04): Mac OS X
• Browser Information: Chrome