Crashes when locking the screen
Or rather, crashes when unlocking the screen or resuming the app. Looking through the comments, I have noticed those of you who stated long ago that the app would sometimes crash when the phone locked, and I experienced the problem a few times myself. A few weeks ago (the 1.12 update I believe) I thought I had tracked down the bug and fixed it. I was testing the app and it seemed fine, thus I submitted the update, only later realizing the issue still existed.
Upon further inspection, I truly found the root of the problem - and it wasn't actually a bug in my code at all. When you lock your phone's screen or switch to a different app, the app goes into a sort of standby mode (tombstoned), where all of the memory of the app is stored but it is not doing anything. However, after a few minutes (not sure of the exact amount of time, but less than 5 minutes) the app is "dehydrated" by the operating system, which is to say the current state of the app is cleaned and removed from memory to free resources for whatever else needs to run. This sounds like a great idea - and it is - but the problem lies with loading the app back into memory when it needs to. It remembered what page the app was on, but none of the variables (page data, images, etc) had been loaded, causing the app to crash instantly. My solution to this problem is to reload all of the data the app needs when it is resumed.
Long story short: the app should no longer crash after being locked for a while, although you may notice a longer load time (less than a second, usually) under such circumstances.