fix: avoid overwriting malformed global config

[kiwigitops]

Summary

• keep malformed global config files from being replaced during config updates
• continue treating missing global config as an empty config
• add a regression test for malformed config preservation

Fixes #1337.

Testing

• npx prettier --check src/lib/schemas/io/global-config.ts src/cli/__tests__/global-config.test.ts
• npx vitest run --project unit src/cli/__tests__/global-config.test.ts

[Hweinstock]

Thanks for taking a look! Looking at this change, we might need a broader refactor here to get the right behavior we're looking for.

[Hweinstock]

it looks like this catch will still silently swallow all errors from downstream. The result is that the user won't see a helpful error message of why the command failed when their config is invalid, but will see that the command failed.

I think this might take a broader refactor to bubble up this error correctly, (and maybe unify these read config methods)

[kiwigitops]

That makes sense. This patch handles the overwrite case, but it still leaves callers without a clean way to distinguish a missing config from a malformed config.

I can rework this around returning the parse/read error from the config-loading path if that matches the direction you had in mind.

[kiwigitops]

Reworked along those lines. updateGlobalConfig now returns { success, error? } instead of a bare boolean, and the config-loading path distinguishes a missing file (start fresh) from a malformed one: on a read/parse/schema failure it leaves the file untouched and returns the error, so callers can tell the two cases apart. telemetry enable/disable now surface the actual reason instead of a generic write warning. Updated the unit tests to cover the malformed case.