For me I reported a similar issue except I experienced it with an Android device so possibly the beta crashing issue me and you are having are the same, that's interesting because that could mean this is cross platform issue. Also if you want to see my issue on this similar problem it is MCPE-129178
For me my case MCPE-129178 seemed to have been a duplicate but I want to add that for some other variants or cases of this issue, at times simply walking in a world generated by Caves and Cliffs experimental option can crash the game.