500 error when user authenticates with GitHub OAuth

Summary

After the authentication via OAuth GitHub, the user will get 500 status code on https://gitlab.com/

Steps to reproduce

1. Open https://gitlab.com/ in browser
2. Click "Sign In"
3. Click "Sign In with GitHub"
4. Finish the authentication with Github
5. Open https://gitlab.com/

What is the current bug behavior?

The user will se the error: 500 status code, "Whoops, something went wrong on our end."

What is the expected correct behavior?

The user can use GitLab as usual.

Relevant logs and/or screenshots