esm support

[jimmywarting]

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not so much is needed to make this full ESM compatible without the need for a build tool...

just need to slam in full relative path and not using extension less paths, esm was not built for that.

Mandatory file extensions #

A file extension must be provided when using the import keyword to resolve relative or absolute specifiers. Directory indexes (e.g. './startup/index.js') must also be fully specified.

This behavior matches how import behaves in browser environments, assuming a typically configured server.