Repair Client AFTER A GAME STARTS?

God this had to be the most infuriating experience I've ever been a part of. I have been playing league, 2 games in or so. Then I enter a third one, and AFTER the lobby finishes and the game starts to launch, rito tells me there's a problem with my files and it has to "repair" said files. So needless to say, the game is a remake, and I get reported.

Pls make a check where if this kind of thing happens, it happens before the game starts loading? And no, I didn't do anything on my computer before starting the next game. No updates, nada.