Error/crash while loading

So i just lost a ranked match because the game crashed while loading, giving me an error (see the attached picture). This has happened twice already, saying that my game files are missing.. The best part is, i can't log in for another 10 minutes since the client demands "checking for corrupt files", what do i have to do for this to not happen again? Edit: After the error i could hear the sounds when champs spawn in the beginning of the match but there was no game i could bring up.