Fixed busines parameter check

src/Utils/LuBusiness.php

      */
     public static function checkParam($param, $validate = null)
     {
-        $value = self::getParam($param);
-        if (is_null($value) || trim($value) == '')
+        if (!self::hasParam($param))
             abort(400, 'Missing parameter: ' . $param);
+        $value = self::getParam($param);
         if ($validate != null) {
             if (is_callable($validate)) {
                 $validate = $validate($value);