@nuxt/types should be a valid JS package (w/ an index.js) so that TS emitDecoratorMetadata works

[fabis94]

Versions

• nuxt: 2.15.3
• node: 14.15.4
• typescript: 4.2.3

Reproduction

No reproduction, but I've shown an example and explained it here: microsoft/TypeScript#18008 (comment)

For more info on the entire issue and how emitDecoratorMetadata see the entire issue: microsoft/TypeScript#18008

Steps to reproduce

Create a TypeScript class in Nuxt.js that is decorated with a TS decorator & with emitDecoratorMetadata turned on, and have one of the constructor params be one of the types exported from @nuxt/types.

What is Expected?

The code should compile.

What is actually happening?

Since emitDecoratorMetadata: true leaves the import of @nuxt/types in JavaScript in the compiled build, webpack throws an error about not being able to resolve @nuxt/types, because the package doesn't have an index.js file.