version should exit nonzero instead of only printing to stderr and bailing

[eckdanny]

Affected Packages

@changesets/cli@<=2.27.1 i.e. this block

Problem

As a CLI user, I expect a nonzero exit status here. Esp in CI scenarios, where the errexit shellopt is nearly always on. The printed warning is helpful.

Proposed solution

Throw an ExitError instead

[eckdanny]

having just tuned up a new CI/CD pipeline with changesets at work, occurs to me this is probably a breaking change. Maintainers are prob more aware of ramifications than me.

Possible semver escape hatch: consider an --exit-code (like git diff) or --strict -like optional arg to maintain current behavior, but give us the option to fail-on-warn if that's what we want. Or consider is-ci-powered "strictness"