fix(cli): throw CliUserError for missing package.json

[posthog-eu]

Summary

Problem

• Running a CLI command outside a project root mints a fresh error tracking issue, spending team triage time on an expected user error where no user is blocked.
• Missing package.json was thrown as a plain Error, so shouldCapturePosthogException sent it to error tracking as an unhandled_error.
• The message interpolated the absolute path, so the fingerprint varied per user and each run could open its own issue.

Changes

• Throw CliUserError (the marker shouldCapturePosthogException skips) at every missing-package.json site, mirroring the earlier "not logged in" and upload-abort fixes.
• Keep the thrown message constant and move the path into CliUserError context, so the fingerprint stays stable. log.error still prints the full, path-specific guidance to the user, so nothing changes for the person running the command.
• Covers three identical sites, not two: readPackageJson, getAllPackagesDependencies, and getDeclaredPackageVersionMap. The report named the first two; the third has the same throw and the same noise, so it is part of the same root cause.

Site	Before	After
readPackageJson	throw new Error(<path-bearing message>)	throw new CliUserError(<constant>, { packageJsonPath })
getAllPackagesDependencies	throw new Error(<path-bearing message>)	throw new CliUserError(<constant>, { packageJsonPath })
getDeclaredPackageVersionMap	throw new Error(<path-bearing message>)	throw new CliUserError(<constant>, { packageJsonPath })

Test plan

• bun run test:package-json-guard — updated to assert the thrown error is a CliUserError, the message is constant (no interpolated path), and the path arrives in context.
• bun run lint — passes.
• bun run typecheck — passes.

Screenshots

Not applicable. The user-facing message is unchanged; log.error still prints the full path and guidance.

Checklist

• My code follows the code style of this project and passes
  bun run lint:backend && bun run lint.
• My change requires a change to the documentation.
• I have updated the documentation
  accordingly.
• My change has adequate E2E test coverage.
• I have tested my code manually, and I have provided steps how to reproduce
  my tests

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[codspeed-hq]

Merging this PR will not alter performance

✅ 43 untouched benchmarks
⏩ 2 skipped benchmarks¹

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_{Comparing posthog-self-driving/fixcli-stop-error-tracking-minting-8c2f1b (db402e1) with main (bac918f)}

Footnotes

1. 2 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud