Ensure CircuitHost disposes DI scope even if other disposals throw

src/Components/Server/src/Circuits/CircuitHost.cs

@@ -293,10 +293,16 @@ namespace Microsoft.AspNetCore.Components.Server.Circuits
 
             await Renderer.InvokeAsync(async () =>
             {
-                await OnConnectionDownAsync(CancellationToken.None);
+                try
-                await OnCircuitDownAsync();
+                {
-                Renderer.Dispose();
+                    await OnConnectionDownAsync(CancellationToken.None);
-                _scope.Dispose();
+                    await OnCircuitDownAsync();
+                }
+                finally
+                {
+                    Renderer.Dispose();
+                    _scope.Dispose();
+                }
             });
         }
 

src/Components/Server/test/Circuits/CircuitHostTest.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Reflection;
 using System.Text.Encodings.Web;
 using System.Threading;
 using System.Threading.Tasks;
@@ -40,6 +41,37 @@ namespace Microsoft.AspNetCore.Components.Server.Circuits
             Assert.True(remoteRenderer.Disposed);
         }
 
+        [Fact]
+        public async Task DisposeAsync_DisposesResourcesEvenIfCircuitHandlerOrComponentThrows()
+        {
+            // Arrange
+            var serviceScope = new Mock<IServiceScope>();
+            var handler = new Mock<CircuitHandler>();
+            handler
+                .Setup(h => h.OnCircuitClosedAsync(It.IsAny<Circuit>(), It.IsAny<CancellationToken>()))
+                .Throws<InvalidTimeZoneException>();
+            var remoteRenderer = GetRemoteRenderer(Renderer.CreateDefaultDispatcher());
+            var circuitHost = TestCircuitHost.Create(
+                Guid.NewGuid().ToString(),
+                serviceScope.Object,
+                remoteRenderer,
+                handlers: new[] { handler.Object });
+
+            var throwOnDisposeComponent = new ThrowOnDisposeComponent();
+            circuitHost.Renderer.AssignRootComponentId(throwOnDisposeComponent);
+
+            // Act
+            await Assert.ThrowsAsync<InvalidTimeZoneException>(async () =>
+            {
+                await circuitHost.DisposeAsync();
+            });
+
+            // Assert
+            Assert.True(throwOnDisposeComponent.DidCallDispose);
+            serviceScope.Verify(scope => scope.Dispose(), Times.Once());
+            Assert.True(remoteRenderer.Disposed);
+        }
+
         [Fact]
         public async Task DisposeAsync_DisposesRendererWithinSynchronizationContext()
         {
@@ -239,5 +271,20 @@ namespace Microsoft.AspNetCore.Components.Server.Circuits
                 Assert.Same(Dispatcher, SynchronizationContext.Current);
             }
         }
+
+        private class ThrowOnDisposeComponent : IComponent, IDisposable
+        {
+            public bool DidCallDispose { get; private set; }
+            public void Configure(RenderHandle renderHandle) { }
+
+            public Task SetParametersAsync(ParameterCollection parameters)
+                => Task.CompletedTask;
+
+            public void Dispose()
+            {
+                DidCallDispose = true;
+                throw new InvalidFilterCriteriaException();
+            }
+        }
     }
 }