I feel like it's fine for languages in a web context to take a "the show must go on" attitude as they do. Partially working webpages (slightly broken html/js/etc) are generally much better than a blank page/error message or none of the js working at all.

Dynamic languages are all about letting the caller decide what makes sense and what doesn't, rather than the callee. If you are too conservative with the input types you allow then it can create unnecessary coupling.