I wouldn't think that you run into type errors often with a mature code base. But that's because you have to deal with this problem sooner or later. In a statically typed language, it is quite obvious what fits where. From my (albeit limited) experience with js, python and ruby, you have to invest a lot of effort into documenting and testing things like function parameters, which would be completely unnecessary in a language with static typing, even if that language has a boring, Java like OO type system.
When you test expected function behaviours, sufficient type testing tends to fall out of that pretty much for free - if your test suite is testing function parameters for the sake of testing function parameters and not for the sake of verifying it gets the right output, then the test suite is deficient.
