Antonio Scandurra
a88b63d83c
Previously, when splicing an edit that deleted all transforms, we would leave the `FoldMap` empty, thus violating a bunch of downstream invariants and e.g. causing the `BufferRows` iterator to not return any buffer row. This commit ensures we always have at least one transform (an isomorphic one, specifically) and adds additional test coverage for the `FoldMap::buffer_rows` method by adding it to the randomized tests.