fix: write errors to stderr

[fsouza]

This is #24, with tests fixed.

Closes #19.
Closes #24.

Helps me with resolving fsouza/prettierd#611 😁

[fsouza]

@mantoni thank you very much for core_d. When you have a chance, can you take a look at this PR?

@n3oney I hope you're OK with me picking your PR :)

[mantoni]

Nice! Thanks a lot ❤️

Would you say this is a breaking change that should be released as a new major? Or is minor fine?

[fsouza]

That's a good point, it's probably safer to treat it as a breaking change: I can image that there are folks out there invoking eslint_d or prettierd and looking at the exit status to decide whether to treat stdout as error or not, which gets broken by this. What do you think?

[n3oney]

That's a good point, it's probably safer to treat it as a breaking change: I can image that there are folks out there invoking eslint_d or prettierd and looking at the exit status to decide whether to treat stdout as error or not, which gets broken by this. What do you think?

Honestly I feel stupid now that I didn't even think of that when I was putting prettierd in my editor. Still have the damn thing replacing my entire code with errors when something's wrong with the syntax.......

So I must agree - this probably is a breaking change, since those people would now get empty error messages, if they did that.

[mantoni]

📦 Released in v6.0.0.