I've got a Google Pixel, the latest version of the Stack Exchange app, and here is the repro video:
Original Link to video gif: http://imgur.com/QJO2Ypc
Also, when I tried to upload this GIF file to this question, again using my phone, choosing the GIF file from the device also crashes the app, hence the Imgur link.
I've edited comments on my phone before, so I know it works/worked. All of a sudden the app is crashing.