The loan officer on this loan file, or null when none is set.

Your request body could not be read, so nothing was changed. error.details.reason says what the problem was.

Your bearer token is missing, or it is not valid. Get a new one from POST /api/v4/authenticate and send it again.

There is nothing here to return. Either the record does not exist, or it belongs to another company and so is not yours to see.

Your body is JSON, but it was not labelled as JSON, so it was not read and nothing was changed. Send it again with Content-Type: application/json.

You have made too many calls, so this one was refused and nothing was changed. Retry-After says how many seconds to wait; sending the same request again after that works.

Any other failure. The shape is the same as every other error reply, so the same code can read it.