public function setCoreErrors($env, $errors = 0)
    {
        $this->swapArgs($env, $errors, $this->running_env, false);
        
        $this->errors[$env] = $errors;
        if (!$this->getCallback($env)) {
            $this->setCallback($env, $this->getDefaultCallback());
        }
        
        return $this;
    }