[DWDS] Fixes hot reload/restart crashes after closing browser tab on web-server device (#2699)

* added NoClientsAvailableException logic

* updated version to prepare for release

* updated version number

* addressed comments

* remove duplicate logging

* updated to throw RpcError

* reverted chnages to _ReloadReportWithMetadata

* updated changelog

* refactored string No clients available for ....

* updated to use kIsolateCannotReload

* updated string

Author: jyameo

dwds/CHANGELOG.md

@@ -1,5 +1,6 @@
-## 26.1.0-wip
+## 26.1.0
 
+- `reloadSources` and `hotRestart` now throw an RPC error with `kServerError` code when `NoClientsAvailableException` is caught (no browser clients are connected), allowing tooling to detect and handle this scenario.
 - `pause` now does not send a `PauseInterrupted` event in
   `WebSocketProxyService` as we didn't actually pause.
 

dwds/lib/src/services/web_socket_proxy_service.dart

@@ -33,6 +33,9 @@ const _pauseIsolatesOnStartFlag = 'pause_isolates_on_start';
 /// closes before the new connection is established, preventing premature isolate destruction.
 const _isolateDestructionGracePeriod = Duration(seconds: 15);
 
+/// Error message when no clients are available for hot reload/restart.
+const kNoClientsAvailable = 'No clients available.';
+
 /// Tracks hot reload responses from multiple browser windows/tabs.
 class _HotReloadTracker {
   final String requestId;
@@ -117,6 +120,16 @@ class _ServiceExtensionTracker {
   }
 }
 
+/// Exception thrown when no browser clients are connected to DWDS.
+class NoClientsAvailableException implements Exception {
+  final String message;
+
+  NoClientsAvailableException._(this.message);
+
+  @override
+  String toString() => 'NoClientsAvailableException: $message';
+}
+
 /// WebSocket-based VM service proxy for web debugging.
 class WebSocketProxyService extends ProxyService {
   final _logger = Logger('WebSocketProxyService');
@@ -504,6 +517,14 @@ class WebSocketProxyService extends ProxyService {
       await _performWebSocketHotReload();
       _logger.info('Hot reload completed successfully');
       return _ReloadReportWithMetadata(success: true);
+    } on NoClientsAvailableException catch (e) {
+      // Throw RPC error with kIsolateCannotReload code when no browser clients are
+      // connected.
+      throw vm_service.RPCError(
+        'reloadSources',
+        vm_service.RPCErrorKind.kIsolateCannotReload.code,
+        'Hot reload failed: ${e.message}',
+      );
     } catch (e) {
       _logger.warning('Hot reload failed: $e');
       return _ReloadReportWithMetadata(success: false, notices: [e.toString()]);
@@ -518,6 +539,14 @@ class WebSocketProxyService extends ProxyService {
       await _performWebSocketHotRestart();
       _logger.info('Hot restart completed successfully');
       return {'result': vm_service.Success().toJson()};
+    } on NoClientsAvailableException catch (e) {
+      // Throw RPC error with kIsolateCannotReload code when no browser clients are
+      // connected.
+      throw vm_service.RPCError(
+        'hotRestart',
+        vm_service.RPCErrorKind.kIsolateCannotReload.code,
+        'Hot restart failed: ${e.message}',
+      );
     } catch (e) {
       _logger.warning('Hot restart failed: $e');
       return {
@@ -611,7 +640,8 @@ class WebSocketProxyService extends ProxyService {
     });
 
     if (clientCount == 0) {
-      throw StateError('No clients available for hot reload');
+      _logger.warning(kNoClientsAvailable);
+      throw NoClientsAvailableException._(kNoClientsAvailable);
     }
 
     // Create tracker for this hot reload request
@@ -671,7 +701,8 @@ class WebSocketProxyService extends ProxyService {
     });
 
     if (clientCount == 0) {
-      throw StateError('No clients available for hot restart');
+      _logger.warning(kNoClientsAvailable);
+      throw NoClientsAvailableException._(kNoClientsAvailable);
     }
 
     // Create tracker for this hot restart request
@@ -737,9 +768,7 @@ class WebSocketProxyService extends ProxyService {
     final request = ServiceExtensionRequest.fromArgs(
       id: requestId,
       method: method,
-      args: args != null
-          ? Map<String, dynamic>.from(args)
-          : <String, dynamic>{},
+      args: <String, Object?>{...?args},
     );
 
     // Send the request and get the number of connected clients
@@ -940,8 +969,8 @@ class WebSocketProxyService extends ProxyService {
   /// Pauses execution of the isolate.
   @override
   Future<Success> pause(String isolateId) =>
-      // Can't pause with the web socket implementation, so do nothing.
-      Future.value(Success());
+  // Can't pause with the web socket implementation, so do nothing.
+  Future.value(Success());
 
   /// Resumes execution of the isolate.
   @override

dwds/lib/src/version.dart

@@ -1,6 +1,6 @@
 name: dwds
 # Every time this changes you need to run `dart run build_runner build`.
-version: 26.1.0-wip
+version: 26.1.0
 
 description: >-
   A service that proxies between the Chrome debug protocol and the Dart VM