fix(@angular-devkit/build-angular): avoid repeat error clear in vite development server

In the Vite-based development server, an error overlay is requested if a build encounters
an error. This error is then cleared when the error is corrected. However, the flag indicating
that the error was cleared was not previously reset. This resulted in additional empty update
commands being sent to the Vite client. While this has no visual effect, it is unneeded additional
processing.

Author: clydin

packages/angular_devkit/build_angular/src/builders/dev-server/vite-server.ts

@@ -151,6 +151,7 @@ export async function* serveWithVite(
       }
       continue;
     } else if (hadError && server) {
+      hadError = false;
       // Send an empty update to clear the error overlay
       server.ws.send({
         'type': 'update',