[FIX] ErrorTracking: Bug everywhere the class is called before initialization

By accessing tiki-objectpermissions.php?group=groupName, an unstyled page is displayed. In fact, the error comes from error tracking. Since PHP 7.4 introduced type hinting for properties with ?, it is especially important to provide valid values ​​for all properties, so that all properties have values ​​that match their declared types. Therefore, a property that has never been assigned does not have a null value, but it is in an undefined state, which therefore does not correspond to any declared type. The way around this problem is to assign values ​​to all properties that match the declared types. And for this case, I think giving null as default guarantees.

This happens everywhere that class is used and there is no value assigned!

Related links: https://avan.tech/item80450