Added error directory to checks + php8.4 fix

[sreichel]

Test php8.4 syntax.

   ! find . -not \( -path ./.phpstorm.meta.php -prune \) -type f -name "*.php" -exec php -d error_reporting=32767 -l {} \; 2>&1 1> /dev/null | grep "^"
  shell: /usr/bin/bash -e {0}
  env:
    COMPOSER_PROCESS_TIMEOUT: 0
    COMPOSER_NO_INTERACTION: 1
    COMPOSER_NO_AUDIT: 1
PHP Deprecated:  Error_Processor::_setSkin(): Implicitly marking parameter $config as nullable is deprecated, the explicit nullable type must be used instead in ./errors/processor.php on line 504