My game keeps crashing and showing me this popup

I don't see how this is an error. Looks intentional to me. /s

When you fire up League, before you hit the "Launch" button, look for a little settings gearbox thing. Somewhere in that menu there should be a scan for errors option. Run that, see if it can fix your game.

the same thing happened to me and i reinstalled the update and i got a leaver buster......