Fix Error 500 on login / fix read file on empty files

[baumerdev]

Login fails if files in /var/log/pwfail/ exist but are empty. I got this error in my /var/log/phplog

[07-May-2024 20:28:25 Europe/Berlin] PHP Fatal error:  Uncaught ValueError: fread(): Argument #2 ($length) must be greater than 0 in /usr/local/emhttp/plugins/dynamix/include/.login.php:23
Stack trace:
#0 /usr/local/emhttp/plugins/dynamix/include/.login.php(23): fread(Resource id #22, 0)
#1 /usr/local/emhttp/plugins/dynamix/include/.login.php(64): readFromFile('/var/log/pwfail...')
#2 /usr/local/emhttp/plugins/dynamix/include/.login.php(198): cleanupFails('/var/log/pwfail...', 1715106505)
#3 /usr/local/emhttp/login.php(37): include('/usr/local/emht...')
#4 {main}
  thrown in /usr/local/emhttp/plugins/dynamix/include/.login.php on line 23

I added an additional check to only open and read the file if the size is greater than 0.

[ljm42]

Great fix, appreciate it!