Hi @Antropus, not sure if you're aware, but I've gotten a few reports of this error after Lightspeed is used:
https://bitbucket.org/jasondavidcarr/launchbox/issues/1179/key-error-on-launch
It looks like somehow either duplicate platforms or duplicate game IDs are being created somewhere, which is ultimately causing crashes. I could make LaunchBox ignore it instead of error out, but then something would be missing from the collection, so I'd rather if we could figure what's causing the issue. Thanks! :)