unable to use from a vscode language server extension

[ryepup]

Describe the bug

Something about the bundling process isn't working right, and I don't know enough about npm/typescript packaging to be clear and concise.

To reproduce

Steps to reproduce the behavior:

1. follow https://code.visualstudio.com/api/language-extensions/language-server-extension-guide to make a stub language server in typescript that you can debug in a new VScode instance (aka Extension Development Host)
2. npm install --save @nginx/reference-lib in the "server" part of the extension
3. add a import { find } from '@nginx/reference-lib'
4. run the server by itself, should work fine via tsc && node out/server.js
5. run the server inside the extension dev host, get an error:

Uncaught Error Error: require() of ES Module .../server/node_modules/@nginx/reference-lib/dist/index.js from .../server/out/server.js not supported.

Futzing around with various arcane tsconfig.json or package.json settings could get different errors, like

Uncaught ReferenceError ReferenceError: exports is not defined in ES module scope This file is being treated as an ES module because it has a '.js' file extension and '...server/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.

or

Uncaught Error Error: Cannot find module '.../server/node_modules/vscode-languageserver/node' imported from .../server/out/server.js Did you mean to import "vscode-languageserver/node.js"?

Expected behavior

Extension dev host can import the library.

Your environment

• node 23.11
• macos

Additional context

Asking AI didn't really help. It just repeatedly told me to set things in json files that I already had, or suggested that the lib needed to be published differently to supports modules and commonjs, but all this packaging stuff is not my area of expertise.