There are some ways to deal with this. Developers can build their own test suites, which automatically check numerous test-cases for various browsers. And they can also wrap each of the functions in their code with exception handlers. But Proxino’s founders say that test suites aren’t perfect (the worst bugs are the ones that slip through these tests), and that many developers don’t want to manually add error handling.
Proxino charges based on the amount of traffic your website draws. There’s a free version for low-traffic sites with less than 1,000 page views per month; the first paid tier is $30/month for up to 10,000 page views (you can see their full price list here).