*This is a follow-up to PR 5966.*
Now that https://bugzilla.mozilla.org/show_bug.cgi?id=1151931 has landed, we're unfortunately in a situation where Firefox warns about `unreachable code after return statement` multiple times when using the PDF.js code in `node make server` mode.
I'm really sorry about the churn in this code!
However I don't think it's a good idea to let Firefox continue to printing these warnings in the console, since it increases the risk of missing actual errors.