Error Encountered with Calendly API - Refresh Token

When I request the Calendly API, I encountered an unexpected error, and I'm not sure what caused it. Could you please explain it to me or make some improvements to your API? I believe I need more specific feedback regarding the error.

The API I requested is "Get Access Token."
https://developer.calendly.com/api-docs/be9b32ef4b44c-get-access-token

In the past, over a considerable period of time, I have received the following errors separately:

bad request: [json.exception.parse_error.101] parse error at line 1, column 1: syntax error while parsing value - invalid literal; last read: '<'
bad request: [json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid literal; last read: 'no'
bad request: [json.exception.parse_error.101] parse error at line 1, column 1: syntax error while parsing value - invalid literal; last read: 'u'
.... <title>auth.calendly.com | 520: Web server is returning an unknown error</title> ......


But according to your documentation, under the 400 status, it should explicitly return the following content:
{
  "error": "invalid_grant",
  "error_description": "The provided authorization grant is invalid, expired, revoked, does not match the redirection URI used in the authorization request, or was issued to another client."
}

But it seems that you are currently throwing unhandled exceptions instead...

Sometimes, these errors appear intermittently, disappearing after a while. However, in some cases, these errors persistently appear in my logging system.


All of the above is extremely distressing, and I would like to know if we have a solution to address these issues together.