Update modifier.truncate.php

[avatec]

For PHP 8.1 if string is empty. Repairs Deprecated: mb_strlen(): Passing null to parameter #1 ($string) of type string is deprecated in vendor/smarty/smarty/libs/plugins/modifier.truncate.php on line 33

[Visualq]

This is BC breaking, considering empty() returns true on "0","false", "", [] and null and your return type is "null" hence the return;

It would be better to:

if ($string === null) { return ''; }

However, the null problem might require a more general fix.

[avatec]

Yes, but i think no one should truncate 0, false or empty array. It should be checked before. We can also use !isset instead of empty.

[wisskid]

Agree with @Visualq here. Also, we're going to needs tons of (string) casts or null checks to weed out every deprecation warning, I guess.