Ran into this while bundling an app with webpack 5 + babel. The arrow function
used as the default export in resolveConfig.js causes __WEBPACK_DEFAULT_EXPORT__
to resolve to undefined under certain babel plugin configurations (specifically
with @babel/plugin-transform-modules-commonjs and module interop settings).

Converting it to a named function export resolves the issue without any
behavioral changes.

Tested with the repro case from #10675.

Summary by cubic

Fixes an issue where resolveConfig’s default export could be undefined when bundling with webpack 5 + babel CommonJS transforms. Converts the arrow default export to a named function and re-exports it as default; no behavior or API changes.

Description

• Change: convert arrow default export to named resolveConfig and default-export it.
• Reason: @babel/plugin-transform-modules-commonjs can break arrow default exports in webpack 5, causing __WEBPACK_DEFAULT_EXPORT__ to be undefined.
• Context: Verified with the repro; merged latest v1.x into this branch with no additional code changes.
• Docs: none required; optional note in /docs/ about babel CommonJS interop and default exports.
• Semver: patch.

Testing

• No test changes; existing tests cover resolveConfig.
• Recommended: add an integration build test using webpack 5 + @babel/plugin-transform-modules-commonjs to prevent regressions.

^{Written for commit eb5978c. Summary will update on new commits. Review in cubic}