tree-sitter is excellent stuff! It's heavily inspired by Tim Wagner's PhD thesis (original site seems to be down, but https://web.archive.org/web/20150919164029/https://www.cs.be... works). IMHO more people should know about that work, and the sequence of work from Susan Graham's lab that led up to it. We have also been heavily inspired by Tim's work and Lukas's thesis extends and updates a number of aspects of that seminal work including, in Chapter 3, error recovery (https://diekmann.co.uk/diekmann_phd.pdf).

All that said, it's surprisingly difficult to compare error recovery in an online parser (i.e. one that's parsing as you type) to a batch parser. In the worst case (e.g. load a file with a syntax error in), online parsers have exactly the same problems as a batch parser; however, once they've built up sufficient context they have different, sometimes more powerful, options available to them (but they also need to be cautious about rewriting the tree too much as that baffles users).