fix: open a new window when creating a page with no existing targets

lib/PuppeteerSharp/Cdp/CdpBrowser.cs

@@ -341,7 +341,9 @@ internal async Task<IPage> CreatePageInContextAsync(string contextId, CreatePage
             WindowState = windowBounds?.WindowState,
 
             // Works around crbug.com/454825274.
-            NewWindow = hasTargets && options?.Type == CreatePageType.Window ? true : null,
+            // When no targets exist (e.g. all pages were closed in headful mode), Chrome has no
+            // browser window. We must request a new window so Chrome can create the page.
+            NewWindow = (!hasTargets || options?.Type == CreatePageType.Window) ? true : null,
             Background = options?.Background,
         };
 
@@ -357,6 +359,7 @@ internal async Task<IPage> CreatePageInContextAsync(string contextId, CreatePage
 
         var targetId = (await Connection.SendAsync<TargetCreateTargetResponse>("Target.createTarget", createTargetRequest)
             .ConfigureAwait(false)).TargetId;
+
         var target = await WaitForTargetAsync(t => ((CdpTarget)t).TargetId == targetId).ConfigureAwait(false) as CdpTarget;
         await target!.InitializedTask.ConfigureAwait(false);
         return await target.PageAsync().ConfigureAwait(false);

lib/PuppeteerSharp/Cdp/Connection.cs

@@ -136,7 +136,18 @@ public void Dispose()
                 _callbacks[id] = callback;
             }
 
-            await RawSendAsync(message, options).ConfigureAwait(false);
+            try
+            {
+                await RawSendAsync(message, options).ConfigureAwait(false);
+            }
+            catch (System.Net.WebSockets.WebSocketException)
+            {
+                // The WebSocket was aborted (e.g. Chrome exited) between the IsClosed check and the send.
+                // Treat this as a closed connection so callers get TargetClosedException instead.
+                Close("WebSocket error");
+                throw new TargetClosedException($"Protocol error({method}): Target closed.", CloseReason);
+            }
+
             return waitForCallback ? await callback.TaskWrapper.Task.WithTimeout(ProtocolTimeout).ConfigureAwait(false) : null;
         }