fix(assets-loader): join public paths with path.posix so remote assets work on Windows

.changeset/assets-loader-posix-public-path.md

@@ -0,0 +1,5 @@
+---
+"@callstack/repack": patch
+---
+
+Fix the assets loader failing on Windows. Public paths for both remote and extracted assets were joined with `path.join`, which rewrites the separators to backslashes on Windows; for remote assets that turned `https://…` into a string `new URL` rejects, so any bundle containing a remote asset failed with `TypeError: Invalid URL`. Both are URLs rather than filesystem paths and are now joined with `path.posix.join`, which produces the same output on Linux and macOS as before.

packages/repack/src/loaders/assetsLoader/convertToRemoteAssets.ts

@@ -26,8 +26,10 @@ export function convertToRemoteAssets({
     .join(assetsDirname, resourceDirname)
     .replace(pathSeparatorRegexp, '/');
 
-  // works on both unix & windows
-  const publicPathURL = new URL(path.join(remotePublicPath, assetPath));
+  // `remotePublicPath` is a URL, not a filesystem path, so it is joined with
+  // `path.posix` — `path.join` would rewrite the separators on Windows and
+  // produce something `new URL` rejects.
+  const publicPathURL = new URL(path.posix.join(remotePublicPath, assetPath));
 
   const size = getAssetSize(assets);
 

packages/repack/src/loaders/assetsLoader/extractAssets.ts

@@ -36,7 +36,10 @@ export function extractAssets(
     .replace(pathSeparatorRegexp, '/');
 
   if (customPublicPath) {
-    publicPath = path.join(customPublicPath, publicPath);
+    // `publicPath` is served over HTTP and always uses forward slashes, so it
+    // is joined with `path.posix` regardless of the platform the bundle is
+    // built on.
+    publicPath = path.posix.join(customPublicPath, publicPath);
   }
 
   const size = getAssetSize(assets);