Improved error messaging for require(ESM) in Node.js
As Eleventy is a command line tool, this offers a bit of wiggle room navigating the CommonJS/ESM divide. That is, until we started bundling application plugins in the core library.
require() of ES Module ./node_modules/@11ty/eleventy/src/Eleventy.js from ./eleventy.config.js not supported. Instead change the require of Eleventy.js in ./eleventy.config.js to a dynamic import() which is available in all CommonJS modules.
This error message is decent! But I think we can do better, and doing better will mean that folks will have an easier time upgrading to Eleventy v3. In order to add my own custom error messaging, I used the Conditional Exports feature (the exports property in package.json):
Conditional Exports are typically used for dual publishing packages. When folks dual publish their packages it often involves additional tooling complexity to convert the code from its format as-written to ESM (or CommonJS). Additionally, that complexity would only be a temporary win: Node.js is adding first-party support for require(ESM) in the future (yay!).
Notably, the above is only necessary because I wanted a custom error message. If you’re fine with Node’s provided error message, don’t do any of this.
