Keyboard crashes

[apsun]

Happens most frequently when switching to the keyboard (causing it to immediately switch back to the previous keyboard), although I have seen it very rarely happen when trying to copy a sticker too. I suspect these are OOMs, but I can't seem to get crash dumps from my device so this is just a hunch.

Probably worth implementing #3 to see if it helps with the memory pressure. But in theory we should never be OOMing at all - maybe our cache isn't purging the images when memory runs low, or maybe we just don't get low memory notifications at all? Maybe we need to explicitly unload images in viewDidDisappear?