Remove error count, warning count when `0`

[wooorm]

✖ 1 message (0 errors, 1 warning) > ✖ 1 message (1 warning).

[sindresorhus]

Since there's only one type now, having message feels a bit verbose. I would rather go with:

⚠ 1 warning

See: https://github.com/sindresorhus/log-symbols

[wooorm]

How about these? Just 1 warning or 1 error in the case of one type, otherwise a total and separate counts?

This would result in a prettier report for programs with only one type of message, but an “extensive” summary for programs which have more types (e.g., mdast, retext).

[sindresorhus]

Oh, didn't realize this is used for other things too. I meant it mostly as a UI tweak for Al** linter, since we only use warnings there.

[wooorm]

😉 Alright I’ll push this, thanks for the suggestion, it’s actually better this way!