Tests are only as good as the person who writes them. Typescript is just another way to build confidence in your codebase. I have found it to be an invaluable tool in large projects especially on teams with various levels of experience.
Well code in general is only as good as the person who writes it. You can write static code that compiles and doesn't work at all, you still need to test it. Only in static languages testing it become way more complicated.
