New user(not admin) login error - by: duds07

Error Log:

2019-08-13 13:52:21.159 ***** ERROR ***** [V8.1.4] ERROR *****
2019-08-13 13:52:21.163 ***** ERROR ***** [V8.1.4] on file 'C:\wamp64\www\projeqtor\model\UserMain.php' at line (435)
2019-08-13 13:52:21.234 ***** ERROR ***** [V8.1.4] cause = Undefined index:
2019-08-13 13:52:44.707 ===== TRACE ===== NEW CONNECTED USER 'daryl'
2019-08-13 13:52:53.391 ***** ERROR ***** [V8.1.4] ERROR *****
2019-08-13 13:52:53.394 ***** ERROR ***** [V8.1.4] on file 'C:\wamp64\www\projeqtor\model\UserMain.php' at line (435)
2019-08-13 13:52:53.397 ***** ERROR ***** [V8.1.4] cause = Undefined index: