This the Mako 5 error handler as a stand-alone package that is ment to be used with Mako 4.5 applications running on PHP 7.

Install the package using composer:

composer require letron/error-compat 

Then open your app/config/application.php configuration file and replace the two Mako error handler services with the letron\error\services\cli\ErrorHandlerService and letron\error\services\web\ErrorHandlerService services.

That's it. You're done!