Files under `dist/esm/` should use the `.mjs` extension

[haoqunjiang]

Being present in the exports field of package.json does not automatically make the file an ES module. It must be ended with .mjs, or the package.json has to include type: "module".

https://nodejs.org/api/packages.html#packages_determining_module_system

[haoqunjiang]

This issue makes the plugin unusable inside vite.config.mjs.

[smashercosmo]

Can't use it in vite.config.ts either. Getting

(node:78771) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)

import resolve from 'resolve';
^^^^^^

SyntaxError: Cannot use import statement outside a module