The following has evaluated to null or missing: ==> a [in template "site_1/category/list.html" at line 29, column 98]

The following has evaluated to null or missing: ==> a [in template "site_1/category/list.html" at line 30, column 121]

The following has evaluated to null or missing: ==> a [in template "site_1/category/list.html" at line 31, column 106]