Fix `html_entity_decode` deprecation warning in PHP 8.1

[AdeAttwood]

Passing null as the second parameter is deprecated in PHP 8.1. When using the legacyConstruct function the htmlFuncFlags are never set and passing null into html_entity_decode.

This move setting htmlFuncFlags above the legacy check to ensure they are always set to prevent passing null into html_entity_decode.

[tinect]

@mtibben could this please be merged and a new release created? :-) Thank you.