I've been having the exact same issue since yesterday, also reported the problem here: https://bitbucket.org/jasondavidcarr/launchbox/issues/2478/crashes-every-time-i-start-the-program
I was downloading some artwork for some games within LaunchBox and had started BigBox various times until one time it didn't open anymore and I was presented with that error message. Haven't been able to open LaunchBox or BigBox since.
I've attached the Data folder if it helps somehow.
Data.zip