feat(canopen): add DisposeAsync, and let a node be disposed from its own event handler

src/CanKit.Pro.CANopen/CanOpenNode.CommunicationProfile.cs

@@ -697,6 +697,9 @@ private void PerformNmtReset(bool communicationOnly)
         // the hook lets the application restore what the description does not hold.
         RaiseApplicationReset(communicationOnly ? NmtCommand.ResetCommunication : NmtCommand.ResetNode);
 
+        // A subscriber may have disposed the node; its timers are gone and nothing is announced.
+        if (Volatile.Read(ref _disposed) != 0) return;
+
         _state = NmtState.PreOperational;
         // Boot-up (0x00) first; a heartbeat with the new state follows only when the producer is
         // active, in which case §7.2.8.3.2.2 regards the boot-up as its first heartbeat — and the

src/CanKit.Pro.CANopen/CanOpenNode.FlyingMaster.cs

@@ -614,7 +614,7 @@ private void RaiseFlyingMaster(FlyingMasterSignal signal, byte? otherNodeId, ush
         var args = new FlyingMasterChangedEventArgs(signal, _flyingMasterRole, otherNodeId, otherPriority);
         // The dispatcher reports a subscriber throw and keeps going, so a timeout or an
         // EMCY already queued is still delivered. A second catch here would only repeat that.
-        EnqueueEvent(() => FlyingMasterChanged?.Invoke(this, args));
+        EnqueueEvent(() => DeliverToSubscribers(FlyingMasterChanged, args));
     }
 
     private OdWriteDecision ValidateFlyingMasterTimingWrite(byte subindex, byte[] value)

src/CanKit.Pro.CANopen/CanOpenNode.NodeGuarding.cs

@@ -332,7 +332,7 @@ private void RaiseLifeGuardingEvent(LifeGuardingState state)
         var args = new LifeGuardingEventArgs(state, _guardTime, _lifeTimeFactor);
         EnqueueEvent(() =>
         {
-            try { LifeGuardingEvent?.Invoke(this, args); }
+            try { DeliverToSubscribers(LifeGuardingEvent, args); }
             catch (Exception ex) { RaiseBackgroundException(ex); }
         });
     }
@@ -354,7 +354,7 @@ private void RaiseNodeGuardingReceived(byte producer, NmtState state, bool toggl
         var args = new NodeGuardingReceivedEventArgs(producer, state, toggle, ts);
         EnqueueEvent(() =>
         {
-            try { NodeGuardingReceived?.Invoke(this, args); }
+            try { DeliverToSubscribers(NodeGuardingReceived, args); }
             catch (Exception ex) { RaiseBackgroundException(ex); }
         }, critical: false, key: null, emcyProducer: -1, producer);
     }
@@ -364,7 +364,7 @@ private void RaiseNodeGuardingTimeout(byte producer, TimeSpan guardTime, byte li
         var args = new NodeGuardingTimeoutEventArgs(producer, guardTime, lifeTimeFactor);
         EnqueueEvent(() =>
         {
-            try { NodeGuardingTimeout?.Invoke(this, args); }
+            try { DeliverToSubscribers(NodeGuardingTimeout, args); }
             catch (Exception ex) { RaiseBackgroundException(ex); }
         }, critical: true, EventKey.NodeGuardingTimeout(producer), emcyProducer: -1, producer);
     }