API: File versionDifferences has 500 error after uploading files to published dataset

[ChengShi-1]

What steps does it take to reproduce the issue?
Find a published dataset.

Upload a new file to this dataset.

After the file is uploaded, call the following API endpoint:
GET http://localhost:8000/api/v1/files/:fileID/versionDifferences

A 500 Internal Server Error is returned.

• Which page(s) does it occur on?
  File /versionDifferences API

• What happens?
  A 500 error occurs when the versionDifferences API is called for a file uploaded to a published dataset.

• To whom does it occur (all users, curators, superusers)?
  All users

• What did you expect to happen?
  The API should return file version difference information without error.