Problem

There's a potential runtime crash in runAllBuildsCommand when using --all-builds with --output:

Location: package/configExporter/cli.ts:681

const targetDir = resolvedOptions.saveDir! // Set by applyDefaults

Root Cause:

• applyDefaults only sets saveDir when !options.stdout && !options.output
• When --output is present, saveDir remains undefined
• Line 681 uses saveDir! (non-null assertion) which will fail at runtime

Missing Validation:
The yargs .check() validates --build vs --all-builds but not --output vs --all-builds.

Proposed Fix

Add validation in the yargs .check() block (around line 306):

if (argv['all-builds'] && argv.output) {
  throw new Error(
    "--all-builds and --output are mutually exclusive. Use --save-dir instead."
  )
}

Additional Improvements

1. Test Coverage Gap

The existing test file (test/package/configExporter.test.js) does not test the applyDefaults function directly.

Recommended tests:

• Default format/annotate for --doctor mode
• Default format/annotate for file save mode (no --stdout/--output)
• Default format/annotate for stdout/output modes
• Default saveDir behavior
• Immutability property (verify original options object is not mutated)

2. Type Safety Enhancement

Consider creating a ResolvedOptions type to eliminate non-null assertions like resolvedOptions.saveDir!. This would catch potential issues at compile-time rather than runtime.

Example:

type ResolvedOptions = ExportOptions & {
  format: 'yaml' | 'json' | 'inspect'
  annotate: boolean
  saveDir?: string // Make explicit when it's set vs not set
}

3. Code Style Simplification (optional)

The applyDefaults function could potentially be more concise using a functional approach, though the current implementation is clear and maintainable.

Priority

Medium-High: The runtime crash is a real issue that could affect users, but it requires a specific combination of flags that may be uncommon.

Related

• Part of ongoing ESLint technical debt cleanup (Code Style: Fix remaining ESLint style issues #709)
• Related to PR Refactor applyDefaults to avoid parameter reassignment #735 (applyDefaults refactoring)

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