Show console errors in game

[ten3roberts]

For example, in Firefox you get a black screen with nothing more to go on if you don't open developer tools

[FredrikNoren]

@ten3roberts It doesn't need to show the actual errors in the game; it's enough if it just shows "Something broke" or equivalent. The actual error is only relevant to the developer of the game. (We should eventually set up some way for people to collect errors from users though, like sentry).