Did the error message dialog look like this?
http://www.mystgraphics.com/OverwatchForumImages/OverwatchCrashDialog.jpg
If so that means the game client has detected something causing it to shut down and it is more than likely related to a system driver or hardware failure on your system rather than a game bug (though that is still possible). This report is handy because it instantly sends important crash data to Blizzard and customer support agents are able to look up the information and possibly provide advice on how to correct it.
That being said I still recommend doing the steps in this Blizzard Support article as well to cover most common issues:
If nothing works, either make a new post in the technical support forum where players like myself or Blizzard customer support can lend a hand, or if you rather work directly work with Blizzard, start a web ticket.
Unfortunately all disconnections and game crashes counts as leaving the match and will be penalized appropriately. The game server has no way to discern a legitimate disconnection or game crash from one that is forcefully caused by a dishonest player to bypass leaver penalties. Furthermore, by penalizing players who have a malfunction they are more likely to stop playing Competitive Play and correct the issue before attempting to play again. You can learn about this policy here: