Fixes PHP8-Bug within CI3

system/helpers/text_helper.php

@@ -357,7 +357,7 @@ if ( ! function_exists('highlight_code'))
 		return str_replace(
 			array('phptagopen', 'phptagclose', 'asptagopen', 'asptagclose', 'backslashtmp', 'scriptclose'),
 			array('<?', '?>', '<%', '%>', '\\', '</script>'),
-			$str
+			$str ?? ''
 		);
 	}
 }