Should warn on login/password error

[olibre]

Steps to reproduce

1. Install Nextcloud-SMS v2.0.5 (2018-12-23) from F-Droid (I did not try Google Play)
2. Add an account with wrong password
3. Synchronize now (I have about 50 SMS in my phone)
4. After some seconds, Nextcloud-SMS says "Synchronisation complete"
5. Go to your Nextcloud instance and select the app "Phone Sync"

Expected behaviour

Nextcloud-SMS should warn that my password is not correct.
Else, if my password is correct, I should see the SMS from my phone on Nextcloud.

Actual behaviour

Nextcloud-SMS behaves as my password is correct.
But the "Phone Sync" tab does not show any SMS, nothing.

This issue is very similar to #201
(I am pretty sure @aguytech entered a wrong password before reinstalling everything)

I have noticed my password was not correct because, some hours after installing Nextcloud-SMS, I attempted to connect to my Nextcloud instance using my phone using the same wrong password. Then my Nextcloud instance said something like "too many wrong logins from the same IP, will try in 30 seconds". I was thinking the Nextcloud-SMS was connecting with the wrong password every 15 minutes...

I have finally removed the Nextcloud-SMS account from the android settings, and filled the same one but with the correct password.

Server configuration

Nextcloud version: 16.0.3

PHP version: 7

Webserver: Apache/2.4.10

HTTPS:

Client configuration

Android version: 9 using ROM "stable Global MIUI 10.3.2.0"

Phone: Mi MIX 3 (perseus)

Nextcloud SMS app version: 2.0.5 (2018-12-23) from F-Droid

[shtrom]

Same issue if the app is not enabled or installed.