PHP warnings when Last Comments Admin is not active

[azett]

Reported by Matthias Mauch - thanks!

Admin area - Plugins - LastCommentsAdmin
Click on "Delete cache" witout LastComment Plugin active.

Notice: Use of undefined constant LASTCOMMENTS_CACHE_FILE - assumed 'LASTCOMMENTS_CACHE_FILE' in weblabor/public/flatpress/fp-plugins/lastcommentsadmin/plugin.lastcommentsadmin.php on line 33

Warning: Cannot modify header information - headers already sent by (output started at weblabor/public/flatpress/fp-plugins/lastcommentsadmin/plugin.lastcommentsadmin.php:33) in weblabor/public/flatpress/fp-includes/core/core.wp-pluggable-funcs.php on line 273

No errors when LastComment Plugin is active.

On local XAMPP wit inactive LastComment Plugin:

[17-Feb-2019 11:20:36 UTC] PHP Warning:  Use of undefined constant LASTCOMMENTS_CACHE_FILE - assumed 'LASTCOMMENTS_CACHE_FILE' (this will throw an Error in a future version of PHP) in weblabor/public/flatpress/fp-plugins/lastcommentsadmin/plugin.lastcommentsadmin.php on line 33
[17-Feb-2019 11:20:38 UTC] PHP Warning:  Use of undefined constant LASTCOMMENTS_CACHE_FILE - assumed 'LASTCOMMENTS_CACHE_FILE' (this will throw an Error in a future version of PHP) in weblabor/public/flatpress/fp-plugins/lastcommentsadmin/plugin.lastcommentsadmin.php on line 38
[17-Feb-2019 11:20:38 UTC] PHP Warning:  Use of undefined constant LASTCOMMENTS_MAX - assumed 'LASTCOMMENTS_MAX' (this will throw an Error in a future version of PHP) in weblabor/public/flatpress/fp-plugins/lastcommentsadmin/plugin.lastcommentsadmin.php on line 49
[17-Feb-2019 11:20:38 UTC] PHP Warning:  A non-numeric value encountered in weblabor/public/flatpress/fp-plugins/lastcommentsadmin/plugin.lastcommentsadmin.php on line 49