Cannot find module in sveltekit project

[stnguyen90]

I wanted to try this out in my sveltekit project and get this error when using the rc.4:

Looking into the index.mjs file, it seems like every import is without a .mjs extension so that it doesn't get resolved.
Adding these file extensions manually fixes the issue.
Is this a tsconfig/package.json/vite config error, so that the wrong file gets looked up, or do those .mjs extensions have to be added?

Originally posted by @eweren in #72 (comment)