Cannot use this in a project with module and moduleResolution of nodenext/node16

[mcmire]

When using this library in a project with module and moduleResolution of nodenext or node16, TypeScript produces compilation errors stemming from Superstruct:

node_modules/superstruct/dist/index.d.ts:1:15 - error TS2834: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Consider adding an extension to the import path.

1 export * from './error';
                ~~~~~~~~~

node_modules/superstruct/dist/index.d.ts:2:15 - error TS2834: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Consider adding an extension to the import path.

2 export * from './struct';
                ~~~~~~~~~~

node_modules/superstruct/dist/index.d.ts:3:15 - error TS2834: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Consider adding an extension to the import path.

3 export * from './structs/coercions';
                ~~~~~~~~~~~~~~~~~~~~~

...

It seems that Superstruct is a ESM library (because its type field in package.json is "module"), but its published TypeScript definition files aren't ESM-compatible. This is tracked a bug here: ianstormtaylor/superstruct#1160

Unfortunately you cannot just change the file extensions, because this library (utils) isn't an ESM library, and you can't import an ESM library in a CommonJS library or else you get an error from TypeScript:

src/versions.ts:9:36 - error TS1479: The current file is a CommonJS module whose imports will produce 'require' calls; however, the referenced file is an ECMAScript module and cannot be imported with 'require'. Consider writing a dynamic 'import("superstruct")' call instead.
  To convert this file to an ECMAScript module, change its file extension to '.mts', or add the field `"type": "module"` to '/Users/elliot/code/metamask/utils/package.json'.

9 import { is, refine, string } from 'superstruct';

So in order to use Superstruct, we either need to fork and fix Superstruct so that it's CommonJS-compatible, or we need to convert this library to use ESM (and make sure it's CommonJS-compatible).

I've started a branch which does both of these things here: convert-to-esm

[mcmire]

The original author of Superstruct seems to have abandoned this project. It is in the hands of a different maintainer, but they are slow to merge changes and fix issues. I think we should fork Superstruct to our org for the time being so that we can get past this issue without having to convert this library to ESM.

[mcmire]

I've created a PR on a fork of Superstruct to address this issue.

In the future, however, we might consider using a different library that is better maintained such as Zod.

[mcmire]

The problems with Superstruct seem to have been solved in the fork that we created, which we published as @metamask/superstruct 2.0.0: https://github.com/MetaMask/superstruct/releases/tag/v2.0.0. I tested this by checking out MetaMask/core#3645 and linking @metamask/utils to a local version which replaced superstruct with @metamask/superstruct, and I didn't see any @metamask/utils-related errors. So I believe we can close this now.