That is a very rare error, but it should be recoverable.
If you didn’t create a backup from the app and you haven’t deleted the old data directory where you can’t open Bisq, you can try perhaps recovering from rolling backups inside ‘btc_mainnet/wallet/backup’ as your wallet seems corrupted.
Make sure you don’t lose any files in the process and always keep backups of every file you replace, just in case.
It would be useful if you know the ID of your last trade and the arbitrator so we can make sure those funds were successfully sent to your address. If you know txid of transactions associated with that trade, that would also help.
PS: You can also read this topic where a user had a similar issue some time ago.