Consider warning about side effects of omitting semicolons

[kumavis]

possible pitfall

google style guide on semicolons
node style guide on semicolons

I'm not saying use semicolons, just pointing out that it can lead to confusing error messages

[mikolalysenko]

True, but I don't want to start a religious war. The right way to do those things is probably to put a semicolon before any expression statement, though it looks a bit awkward. I'll think about the best way to work this into the text.

[kumavis]

I agree there, and AFAIK its the only case where you would run into that.