Hi @Tania Magdieva, thanks for reporting! We definitely need to fix that crash, sorry you ran into it. Regarding the backup, you should also be able to use the Revision History option under the main menu to recover an older version of the file.
I think part of what is making this confusing right now is that we don’t highlight the artboard in the Hierarchy when it’s selected. #134
We could prevent you from deleting an artboard in Animate mode (we used to do this in Flare). Our preference would be not to do that, we don’t want to create too many limits.
We think it’s ok for a user to make a mistake, provided they can recover from it without pain. That way they learn the system and have more flexibility.
Let’s see how it feels once we fix this crashing bug!