Error when taking offer & now app won't shut down

I tried to use the Bisq application today for the first time in several months. I updated to the latest version, accepted a buy offer, transferred the bitcoins from an external wallet, and got the following:

(The trade amount which I accepted was within the trade limit listed in the buy offer. There was nothing to indicate that it was higher than the “peer trade limit”.)

I then tried to quit the application but it’s just hanging. The bitcoins have left my external wallet and I didn’t catch the wallet they were transferred to. I don’t want to lose them, or my trading history, so I haven’t force-quit the app yet. Is there any data I should manually back up before force-quitting the app? Any other suggestions for how to continue?

Update: Everything ok now. Backed everything up. Force-quit application. Restarted. Funds are there. History is all there.

(Actually I transferred 0.1314949 BTC and have 0.1306472 in my funds so .0008477 bitcoins were lost in the failed transaction, which is about 3 Euros.)

Yes, that’s the thing to do.
Backup all your data directory before force-quiting.

In your task manager, you can also force-quit progressively.
At least in linux, you have 3 levels for stopping : stop/stop/kill.
Begin with the smoother stop, see if it suffices. If not, next. If not kill.

Sorry for the little loss.
The repo is provided for reimbursement asking.
Just fill properly your issue.