So how about using a tool like jslint that will get you 90% of the static checking and will solve the kind of crash you mentioned ? Looks pretty good to me.
Does jslint handle imports? Which would be surprising, given the lack of a standard system in Javascript? If it doesn't, then this leaves you very far from your 90%.
On the other hand, pylint for Python is really good for static checking, even if it won't catch everything.
