fix php8 deprecations

Author: connorhu

lib/helper/TextHelper.php

@@ -50,7 +50,7 @@ function truncate_text($text, $length = 30, $truncate_string = '...', $truncate_
 
     if ($strlen($text) > $length) {
         if ($truncate_pattern) {
-            $length_min = null !== $length_max && (0 == $length_max || $length_max > $length) ? $length : null;
+            $length_min = null !== $length_max && (0 == $length_max || $length_max > $length) ? $length : 0;
 
             preg_match($truncate_pattern, $text, $matches, PREG_OFFSET_CAPTURE, $length_min);
 

lib/util/sfToolkit.class.php

@@ -245,6 +245,10 @@ public static function arrayDeepMerge()
      */
     public static function stringToArray($string)
     {
+        if (null === $string) {
+            return array();
+        }
+
         preg_match_all('/
       \s*((?:\w+-)*\w+)     # key                               \\1
       \s*=\s*               # =