Repro steps: 1. Make a Rust file and check it in to git 2. Delete a lot of the file 3. Expand all the diffs (cmd+") 4. Select larger syntax node (ctrl+cmd+right) 5. Collapse all the diffs 6. Select smaller syntax node (ctrl+cmd+left) 7. Panic! The problem was we were using byte offsets instead of anchors so after we shrank the buffer by collapsing diffs we'd be pointing past the end of it. Release notes: - N/A