[Blazor] Don't invoke when connection closed (#31862)

Author: BrennanConroy

dist/Release/blazor.server.js

@@ -1,6 +1,7 @@
 import { internalFunctions as navigationManagerFunctions } from '../../Services/NavigationManager';
 import { toLogicalRootCommentElement, LogicalElement } from '../../Rendering/LogicalElements';
 import { ServerComponentDescriptor } from '../../Services/ComponentDescriptorDiscovery';
+import { HubConnectionState } from '@microsoft/signalr';
 
 export class CircuitDescriptor {
   public circuitId?: string;
@@ -19,6 +20,9 @@ export class CircuitDescriptor {
       throw new Error('Circuit host not initialized.');
     }
 
+    if (reconnection.state !== HubConnectionState.Connected) {
+      return Promise.resolve(false);
+    }
     return reconnection.invoke<boolean>('ConnectCircuit', this.circuitId);
   }
 
@@ -31,7 +35,9 @@ export class CircuitDescriptor {
   }
 
   public async startCircuit(connection: signalR.HubConnection): Promise<boolean> {
-
+    if (connection.state !== HubConnectionState.Connected) {
+      return false;
+    }
     const result = await connection.invoke<string>(
       'StartCircuit',
       navigationManagerFunctions.getBaseURI(),