How to get body text from response when exception occurs (HTTP 400)

[kevinric7]

If my server responds with a 400 Bad Request, this client processes it as an exception. How do i then get access to the body of the response. This exception message only includes the "400" code. I would also like the text which describes the error (example: wrong password")

RestClient.Post<LoginResponseDto>(request)
.Then(response => {
    Debug.Log(JsonUtility.ToJson(response, true));
})
.Catch(err => {
    Debug.Log("Error message: " + err.Message); //value is: "Error message: HTTP/1.1 400 Bad Request"
});

I'm looking for the text that's in the ReponseHelper downloadHandler. I see the desired text when I log it from inside the Error method ReponseHelper, but how do I get it from the Catch above? Thanks!

public string Error
{
    get {
        Debug.Log("response helper text " + Request.downloadHandler.text);
        return Request.error;
    }
}