Commit 4fea9cffbda89562bfdcdd58b0162d31ca4feb3e

Edward Thomson 2016-02-16T13:08:55

iterator: assert tree_iterator has a frame Although a `tree_iterator` that failed to be properly created does not have a frame, all other `tree_iterator`s should. Do not call `pop` in the failure case, but assert that in all other cases there is a frame.