This is reproducible (at least for me) :
1 - Turn off bluetooth from within the app
2 - When you get the "disconnected...do you wish to reconnect?" popup select "No"
3 - Turn bluetooth back on from within the app
This always causes a crash for me. (I'm usually doing some combination of this and shutting my phone on/off to be able to get a full reading)
On its own its not much of an annoyance or anything, I'm just posting it here in case it can help to track down any bluetooth/connectivity bugs.