Don't remove the token when an `invalid_request` occurs

[ruipenso]

The invalid_request is only sent due to missing or invalid parameters which are programmatic errors and should not be checked in runtime.

https://github.com/seegno/angular-oauth2/blob/master/src/interceptors/oauth-interceptor.js#L20

[Gp2mv3]

I also faced this issue. I think it's not useful to remove the token indeed.

[ruipenso]

@Gp2mv3 Cool. Is good to know other developers shares the same opinion.