fix(cloud_firestore, web): stop FirebaseError appearing in console on hot restart & hot refresh (#9321)

Author: russellwheatley

packages/cloud_firestore/cloud_firestore/lib/src/firestore.dart

@@ -108,7 +108,15 @@ class FirebaseFirestore extends FirebasePluginPlatform {
   void useFirestoreEmulator(String host, int port, {bool sslEnabled = false}) {
     if (kIsWeb) {
       // use useEmulator() API for web as settings are set immediately unlike native platforms
-      _delegate.useEmulator(host, port);
+      try {
+        _delegate.useEmulator(host, port);
+      } catch (e) {
+        final String code = (e as dynamic).code;
+        // this catches FirebaseError from web that occurs after hot reloading & hot restarting
+        if (code != 'failed-precondition') {
+          rethrow;
+        }
+      }
     } else {
       String mappedHost = host;
       // Android considers localhost as 10.0.2.2 - automatically handle this for users.