This bug appears to be triggered if you have the "Speak Selection" preference turned on. (Settings, General, Accessibility, Speak Selection.) Turning off this preference will prevent the crash. I will try to fix this in future releases.
This is a nuisance, all right. Unfortunately, I can’t just fill the auto-correction dictionary with IF-specific words. iOS doesn’t support that sort of thing.
You can turn off auto-correction entirely by going to the “Settings” tab in the app. However, auto-correction is usually more right than wrong, I find. Remember that if you want to cancel a particular correction, you can tap the pop-up label. The little × is a close box, secretly.
Over time, playing The Dreamhold will train the iOS dictionary to accept common IF words. Or, at least, complain about them less often.