Don't log OperationCanceledException every time an HMR client disconnects

src/Microsoft.AspNetCore.SpaServices/Webpack/ConditionalProxyMiddleware.cs

@@ -97,9 +97,17 @@ namespace Microsoft.AspNetCore.SpaServices.Webpack
                 context.Response.Headers.Remove("transfer-encoding");
 
                 using (var responseStream = await responseMessage.Content.ReadAsStreamAsync())
+                {
+                    try
                     {
                         await responseStream.CopyToAsync(context.Response.Body, DefaultHttpBufferSize, context.RequestAborted);
                     }
+                    catch (OperationCanceledException)
+                    {
+                        // The CopyToAsync task will be canceled if the client disconnects (e.g., user
+                        // closes or refreshes the browser tab). Don't treat this as an error.
+                    }
+                }
 
                 return true;
             }