Occasional error on disconnect (websockets)

Sometimes when the browser tab is closed a few error messages will be thrown on the server and then a repeating error message which hangs the server completely. Generally clients can disconnect perfectly fine but ~1/20 times this happens.

InvalidOperationException: The current state of the connection is not Open.
WebSocketSharp.WebSocket.Send (System.Byte[] data) (at Library/PackageCache/com.community.netcode.transport.websocket@858f6df327/Runtime/Libraries/websocket-sharp/websocket-sharp/WebSocket.cs:3370)
Netcode.Transports.WebSocket.WebSocketPeer.Send (System.Byte[] data) (at Library/PackageCache/com.community.netcode.transport.websocket@858f6df327/Runtime/WebSocketPeer.cs:25)
Netcode.Transports.WebSocket.WebSocketServerConnectionBehavior.Send (System.UInt64 clientId, System.ArraySegment`1[T] data) (at Library/PackageCache/com.community.netcode.transport.websocket@858f6df327/Runtime/WebSocketServerConnectionBehavior.cs:75)
Netcode.Transports.WebSocket.WebSocketTransport.Send (System.UInt64 clientId, System.ArraySegment`1[T] data, Unity.Netcode.NetworkDelivery delivery) (at Library/PackageCache/com.community.netcode.transport.websocket@858f6df327/Runtime/WebSocketTransport.cs:91)
Unity.Netcode.NetworkManager+NetworkManagerMessageSender.Send (System.UInt64 clientId, Unity.Netcode.NetworkDelivery delivery, Unity.Netcode.FastBufferWriter batchData) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:179)
Unity.Netcode.MessagingSystem.ProcessSendQueues () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Messaging/MessagingSystem.cs:768)
Unity.Netcode.NetworkManager.OnNetworkPostLateUpdate () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:1641)
Unity.Netcode.NetworkManager.NetworkUpdate (Unity.Netcode.NetworkUpdateStage updateStage) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:1538)
Unity.Netcode.NetworkUpdateLoop.RunNetworkUpdateStage (Unity.Netcode.NetworkUpdateStage updateStage) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkUpdateLoop.cs:185)
Unity.Netcode.NetworkUpdateLoop+NetworkPostLateUpdate+<>c.<CreateLoopSystem>b__0_0 () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkUpdateLoop.cs:268)

NullReferenceException: Object reference not set to an instance of an object
Unity.Netcode.FastBufferWriter.Dispose () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Serialization/FastBufferWriter.cs:121)
Unity.Netcode.MessagingSystem.CleanupDisconnectedClient (System.UInt64 clientId) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Messaging/MessagingSystem.cs:438)
Unity.Netcode.MessagingSystem.ClientDisconnected (System.UInt64 clientId) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Messaging/MessagingSystem.cs:429)
Unity.Netcode.NetworkManager.OnClientDisconnectFromServer (System.UInt64 clientId) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:2159)
Unity.Netcode.NetworkManager.HandleRawTransportPoll (Unity.Netcode.NetworkEvent networkEvent, System.UInt64 clientId, System.ArraySegment`1[T] payload, System.Single receiveTime) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:1875)
Unity.Netcode.NetworkManager.OnNetworkEarlyUpdate () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:1596)
Unity.Netcode.NetworkManager.NetworkUpdate (Unity.Netcode.NetworkUpdateStage updateStage) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:1532)
Unity.Netcode.NetworkUpdateLoop.RunNetworkUpdateStage (Unity.Netcode.NetworkUpdateStage updateStage) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkUpdateLoop.cs:185)
Unity.Netcode.NetworkUpdateLoop+NetworkEarlyUpdate+<>c.<CreateLoopSystem>b__0_0 () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkUpdateLoop.cs:208)

This is the error message that loops and hangs the server:

NullReferenceException: Object reference not set to an instance of an object
Unity.Netcode.MessagingSystem.ProcessSendQueues () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Messaging/MessagingSystem.cs:756)
Unity.Netcode.NetworkManager.OnNetworkPostLateUpdate () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:1641)
Unity.Netcode.NetworkManager.NetworkUpdate (Unity.Netcode.NetworkUpdateStage updateStage) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkManager.cs:1538)
Unity.Netcode.NetworkUpdateLoop.RunNetworkUpdateStage (Unity.Netcode.NetworkUpdateStage updateStage) (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkUpdateLoop.cs:185)
Unity.Netcode.NetworkUpdateLoop+NetworkPostLateUpdate+<>c.<CreateLoopSystem>b__0_0 () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Core/NetworkUpdateLoop.cs:268)

Unity 2022.2.0b16
Netcode for GameObjects 1.2.0

Start by reproducing the browser-tab disconnect using the WebSocket transport, then inspect WebSocketPeer.cs, WebSocketServerConnectionBehavior.cs, WebSocketTransport.cs, and the MessagingSystem stack-trace locations. Done means the intermittent disconnect no longer produces repeated errors or hangs the server, while normal client disconnects continue to work.