Do you have any more details? (For instance, where the crash occurred?)
Depending on several factors, you may be able to bypass this error if you reload.
Hey, fair enough, I'll see if I can reproduce it. Thanks for the tip!
EDIT: I have managed to reproduce the error. I'll add a fix for this issue as well as some of the others you mentioned here in the next update. For now though, for yourself and those who might be reading, if you've got a card "grabbed" while in the deck editor, DON'T back out of the editor! Drop the card first!
EDIT 2: Should be fixed as of version 2. I also went ahead and addressed the other two things you mentioned (accidental text skipping and finding the isolated guard). See Patch Notes #1.