codeigniter v4 rc for upcomming project

@MGatner,
I have vague memories with  an upgrade to a CI3 Version or maybe even a CI2 Version that required an Application additional file to be added otherwise errors would be thrown.

Is it possible to eliminate this missing file problem by testing for existence and supplying defaults? Same applies to most of the application files, if not which application files are essential?

I think it would be good to just include the system folder in the index.php and to supply defaults for every application file.