oauth2: invalid_client in callback

[theCapypara]

Trying to finish the OAuth flow always results in this error:

OAuth token exchange failed: invalid_client: client_id is required. error=invalid_client&error_description=client_id+is+required.

The client ID is set, otherwise the banner wouldn't have appeared. I also checked, the code in the callback is valid as well.
Callback URL: http://127.0.0.1:4567/oauth/callback?code=<redacted>&state=<redacted>

[theCapypara]

I think the issue is that trmnlp is ignoring oauth_token_request_auth_method. I have it set to "" (empty) and that defaults to sending the auth info via body on core, but trmnlp always sends them via header.

[sd416]

@theCapypara can you please try from https://github.com/sd416/trmnlp main branch?