check for contraints before executing it

src/Utils/Dbo/LuDbo.php

 
     /**
      * @param $constraints LuParameterConstraintDbo[]
+     * @throws LuDboConstraintException
      */
     public function checkConstraints($constraints) {
         foreach ($constraints as $constraint) {
+            if (!is_callable([$this, $constraint->getMethod()])) {
+                throw new LuDboConstraintException("Constraint '" . $constraint->getMethod() . "' could not be found");
+            }
             call_user_func_array([$this, $constraint->getMethod()], $constraint->getArguments());
         }
     }