fix(types): make StaticImport/TypeImport imports optional

[MFA-G]

Fixes #349

Problem

ESM_STATIC_IMPORT_RE has an optional imports capture group, because a side effect import has no import clause:

import\s*(?:[\s"']*(?<imports>...)from\s*)?["']...
                                          ^ optional

So for a side effect import the property is simply absent at runtime:

findStaticImports('import "styles.css";')[0].imports // => undefined

But StaticImport['imports'] (and TypeImport['imports']) declared it as a required string. TypeScript therefore told consumers the value was always present, and code like match.imports.includes("type") type-checked cleanly while throwing at runtime.

The existing suite has a side effect import case, but it only asserts the specifier, so it never caught the mismatch.

Fix

• imports is now imports?: string on StaticImport and TypeImport, with a doc comment explaining when it is undefined.
• clearImports accepts string | undefined. Its body already did (imports || ""), so this only makes the signature match the behaviour it already had — parseStaticImport / parseTypeImport keep working unchanged on side effect imports.
• findTypeImports guards the filter with match.imports ?? "", which was the one place that fed the possibly-undefined value straight into RegExp.test (it previously relied on test stringifying undefined to "undefined").
• Added a regression test asserting imports is undefined and that parseStaticImport still yields empty namedImports.

Compatibility

This is a type-only change for a value that was already undefined at runtime. It is strictly more accurate, though downstream code that assumed a non-optional string under strict will now surface the guard it was always missing — which is the point of the issue.

Validation

• vitest run — 199/199 pass (6 files)
• tsc --noEmit — clean
• eslint src test — clean
• prettier --check src test — clean
• unbuild — builds successfully

Summary by CodeRabbit

• New Features

  • Added support for side-effect imports without named import clauses.
  • Import analysis now safely handles missing import details.

• Bug Fixes

  • Improved handling of undefined import values while preserving existing cleanup behavior.

• Tests

  • Added coverage confirming side-effect imports are represented correctly and parsed with no named imports.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: aed10620-ccad-463c-a37d-fea41fefb99c

📥 Commits

Reviewing files that changed from the base of the PR and between beece9b and ef8eb3a.

📒 Files selected for processing (3)

• src/_utils.ts
• src/analyze.ts
• test/imports.test.ts

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📝 Walkthrough

Walkthrough

The import analysis types now allow missing import clauses for side-effect imports. Utility handling accepts undefined values, type-import filtering uses a safe fallback, and tests verify the parsed side-effect import shape.

Changes

Side-effect import support

Layer / File(s)	Summary
Optional import clause contracts src/analyze.ts, src/_utils.ts	StaticImport.imports and TypeImport.imports are optional. clearImports accepts undefined values. Type-import filtering handles missing clauses with an empty fallback.
Side-effect import validation test/imports.test.ts	Tests verify that import "styles.css"; has an undefined raw import clause and an empty parsed named-import map.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the primary change: making StaticImport and TypeImport imports optional.
Linked Issues check	✅ Passed	The changes address issue #349 by making imports optional, handling undefined values, and adding regression coverage for side-effect imports.
Out of Scope Changes check	✅ Passed	All code and test changes support the linked issue and stated objective; no unrelated changes are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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