Sort of a good news/bad news update for everyone here: I looked into the errors more and while I have a better idea of what's going on, I don't have a quick fix. The crash has happened on both iPhones and iPads, so it's not specific to the device type. It is, however, always on older devices, iPhones 5 and older and iPad Airs and older, and it looks like the log might be misleading because the actual issue has to do with the device memory being low.
I logged into an account that was seeing the crash on the iPhone 5 simulator and didn't get a crash then, so it's not anything specific to the hardware that shipped with those devices, but rather the state of the individual device.
Reinstalling may help, though a couple people have said they tried that to no avail.
In summary I'll keep looking for possible ways that the app could be responsible for using a ton of memory but there isn't an obvious place where this could be going wrong so... hold tight for now? Sorry for the hassle everyone.