Fix over-sanitization for texts in MD_STD_IN

MD_STD_IN.php

@@ -47,7 +47,9 @@ final public static function sanitize_text($input):string {
 
         $output = \filter_var($input,
             FILTER_SANITIZE_STRING,
-            FILTER_FLAG_NO_ENCODE_QUOTES) ?: "";
+            FILTER_FLAG_NO_ENCODE_QUOTES);
+
+        if ($output === false) return "";
 
         return trim($output);