public function getCallback($env = null)
    {
        $env = $env ?: $this->running_env;
        return isset($this->callbacks[$env]) ? $this->callbacks[$env] : null;
    }
public function getCallback($env = null)
    {
        $env = $env ?: $this->running_env;
        return isset($this->callbacks[$env]) ? $this->callbacks[$env] : null;
    }
public function getCallback ( $ env = null ) { $ env = $ env ? : $ this -> running_env ; return isset ( $ this -> callbacks [ $ env ] ) ? $ this -> callbacks [ $ env ] : null ; }
Returns the callback that will be called when an error is handled

Uses the currently running environment when none is given.

@param  string|null $env Name of the environment

@return callable
Returns the callback that will be called when an error is handled