fix(app): remove trailing commas from routes

[raizorlol]

Fixes "Routes parsing error, maybe a trailing comma or an external variable, trying to fix that later after sources scanning." error when that error occurs due to trailing commas (by removing trailing commas for all possible cases) + a bit of refactoring

[vogloblinsky]

Hi,
thanks for this great PR.
Is it possible to add unit tests ?
I can guide you if needed.

[raizorlol]

Done. The check was added inside the existing test case that tests loadChildren syntax because trailing comma is a possible part of that syntax.

[vogloblinsky]

Thanks !