I think this issue is related to previously reported one in following link.
I guess, in that post, reimporting might be done while execution is staying in ‘Delay’ node, so the next time when ‘Play Animation’ is executed, CurrentTime can be beyond reimported length of anim sequence.
It’s only my guess not confirmed fact, but , I believe you can check out what was the main cause and how Lina fixed that problem.
Saddly, this problem still exist in ue 4.10.1, though it’s not common case. My project is not using blueprint like in the old post, but crashed at the same line while playing preview in animation editor window right after opened animation is reimported.
I hope this help you to figure out the problem at least a little bit.