Fix PHP Notice

[federico.domizi3]

When I go in the pages of a product I have these 3 notice

[Thu Sep 24 09:44:43.764879 2015] [:error] [pid 3941] [client 127.0.0.1:47505] PHP Notice:  Trying to get property of non-object in /var/www/prestashop/tools/smarty/sysplugins/smarty_internal_templatebase.php(157) : eval()'d code on line 191, referer: http://www.prestashop.lc/it/57-anfibi-scarpe-outdoor
[Thu Sep 24 09:44:43.764937 2015] [:error] [pid 3941] [client 127.0.0.1:47505] PHP Notice:  Trying to get property of non-object in /var/www/prestashop/tools/smarty/sysplugins/smarty_internal_templatebase.php(157) : eval()'d code on line 195, referer: http://www.prestashop.lc/it/57-anfibi-scarpe-outdoor
[Thu Sep 24 09:44:43.764951 2015] [:error] [pid 3941] [client 127.0.0.1:47505] PHP Notice:  Trying to get property of non-object in /var/www/prestashop/tools/smarty/sysplugins/smarty_internal_templatebase.php(157) : eval()'d code on line 198, referer: http://www.prestashop.lc/it/57-anfibi-scarpe-outdoor

I want to fix it but I do not know which file tpl or phph is the error.