[core] Include TS modules in rollup import resolution

[michaldudak]

Fixes the problem discussed in #28074 (comment) by searching for index.ts in addition to index.js in rollup config.

[mui-pr-bot]

No bundle size changes (experimental)

Generated by 🚫 dangerJS against 6f2f3a3

[eps1lon]

Looks good.

In the future you could remove the custom resolveId entirely in favor of using the exports field. For example,

diff --git a/packages/material-ui-unstyled/package.json b/packages/material-ui-unstyled/package.json
index 106e9d89b5..41841c3c46 100644
--- a/packages/material-ui-unstyled/package.json
+++ b/packages/material-ui-unstyled/package.json
@@ -5,6 +5,10 @@
   "author": "Material-UI Team",
   "description": "Unstyled React components with which to implement custom design systems.",
   "main": "./src/index.js",
+  "exports": {
+    "./ModalUnstyled": "./src/ModalUnstyled/index.ts",
+    "./*": "./src/*/index.js"
+  },
   "keywords": [
     "react",
     "react-component",

already works but you have to hard-code the modules written in TS and make sure you're not publishing the package with exports.

[michaldudak]

All right, I'll take a look at it in another PR. I think we could even default to index.ts and avoid having .js and .d.ts with mostly the same content in each component's directory.