fix(dev): handle rebuilds that start before previous one finished (#6155)

Author: pcattori

integration/hmr-test.ts

@@ -231,16 +231,16 @@ test("HMR", async ({ page }) => {
   let dev = execa("npm", ["run", "dev"], { cwd: projectDir });
   let devStdout = bufferize(dev.stdout!);
   let devStderr = bufferize(dev.stderr!);
-  await wait(
-    () => {
-      let stderr = devStderr();
-      if (stderr.length > 0) throw Error(stderr);
-      return /✅ app ready: /.test(devStdout());
-    },
-    { timeoutMs: 10_000 }
-  );
-
   try {
+    await wait(
+      () => {
+        let stderr = devStderr();
+        if (stderr.length > 0) throw Error(stderr);
+        return /✅ app ready: /.test(devStdout());
+      },
+      { timeoutMs: 10_000 }
+    );
+
     await page.goto(`http://localhost:${appServerPort}`, {
       waitUntil: "networkidle",
     });

packages/remix-dev/devServer_unstable/index.ts

@@ -63,6 +63,7 @@ export let serve = async (
         }
       },
       onRebuildStart: () => {
+        state.buildHashChannel?.err();
         clean(config);
         websocket.log("Rebuilding...");
       },
@@ -81,7 +82,9 @@ export let serve = async (
             state.appServer = startAppServer(options.command);
           }
         }
-        await state.buildHashChannel.result;
+        let { ok } = await state.buildHashChannel.result;
+        // result not ok -> new build started before this one finished. do not process outdated manifest
+        if (!ok) return;
 
         if (manifest.hmr && state.prevManifest) {
           let updates = HMR.updates(config, manifest, state.prevManifest);