Select.php Error: Index Not Defined on Magento 1.9 with PHP 7.1

Does anyone know why I get this error in System.log when running Magento 1.9.3.10 on PHP 7.1?

ERR (3): Notice: Undefined index: label in /home/ronniebergfel/domains/4x4offroad.se/public_html/app/code/core/Mage/Adminhtml/Block/Widget/Grid/Column/Filter/Select.php en line 76

When running on PHP 5.4, I do not get this error. No idea how to solve that?

Sincerely Ronnie