launchAndKill checks for simulator directories to be present before fina...

...lly killing. Fixes 2612
Yeah I wasn't really how to handle that bit. I think I figured that adding the commit here would link the two pull requests? The commit SHA is preserved on PR's being accepted, right? If so, then this would still work and the only danger is that things get merged in a different order, leaving this as a merge conflict.

What's a better way of doing cross-module PRs?