Agree with this. I've had a large JavaScript codebase where there were so many annoying edge cases mostly caused by variables being null/undefined when you didn't expect it and string/arrays values being mixed up. You could track them down eventually but there was always a feeling of unease that there was more bugs there. If you start using TypeScript with its non-null checking feature and type checking, you can catch so many of these kinds of bugs before even running the code and have high confidence you got them all.
