Oh yeah, but I'm talking about the internal Git state just genuinely being broken, for example: https://stackoverflow.com/questions/14448326/git-commit-stopped-working-error-building-trees
Ultimately, if you spend half an hour debugging that, it just starts being a waste of time compared to cloning anew.

As for how to merge, yes, one should learn that. The problem is that the complexity of the code changes adds on top of whatever insecurities you might still have with Git.
I did put "inexperienced" in braces there, because even as an experienced dev, merges are sometimes just not worth doing. In that case, you could just checkout the branch a second time, but well, still not that different.