Fix QUIC ConnectionState NRE in HandleEventConnectionClose (#57655)

Moved ConnectionState assignment before msquic callback registration to avoid NRE in callback, in case Connection gets closed during Stream's ctor.

Fixes #55815

src/libraries/System.Net.Quic/src/System/Net/Quic/Implementations/MsQuic/MsQuicStream.cs

@@ -95,6 +95,14 @@ public void Cleanup()
  // inbound.
  internal MsQuicStream(MsQuicConnection.State connectionState, SafeMsQuicStreamHandle streamHandle, QUIC_STREAM_OPEN_FLAGS flags)
  {
+ if (!connectionState.TryAddStream(this))
+ {
+ throw new ObjectDisposedException(nameof(QuicConnection));
+ }
+ // this assignment should be done before SetCallbackHandlerDelegate to prevent NRE in HandleEventConnectionClose
+ // but after TryAddStream to prevent unnecessary RemoveStream in finalizer
+ _state.ConnectionState = connectionState;
+
  _state.Handle = streamHandle;
  _canRead = true;
  _canWrite = !flags.HasFlag(QUIC_STREAM_OPEN_FLAGS.UNIDIRECTIONAL);
@@ -117,14 +125,6 @@ internal MsQuicStream(MsQuicConnection.State connectionState, SafeMsQuicStreamHa
  throw;
  }
 
- if (!connectionState.TryAddStream(this))
- {
- _state.StateGCHandle.Free();
- throw new ObjectDisposedException(nameof(QuicConnection));
- }
-
- _state.ConnectionState = connectionState;
-
  _state.TraceId = MsQuicTraceHelper.GetTraceId(_state.Handle);
  if (NetEventSource.Log.IsEnabled())
  {
@@ -140,6 +140,14 @@ internal MsQuicStream(MsQuicConnection.State connectionState, QUIC_STREAM_OPEN_F
  {
  Debug.Assert(connectionState.Handle != null);
 
+ if (!connectionState.TryAddStream(this))
+ {
+ throw new ObjectDisposedException(nameof(QuicConnection));
+ }
+ // this assignment should be done before StreamOpenDelegate to prevent NRE in HandleEventConnectionClose
+ // but after TryAddStream to prevent unnecessary RemoveStream in finalizer
+ _state.ConnectionState = connectionState;
+
  _canRead = !flags.HasFlag(QUIC_STREAM_OPEN_FLAGS.UNIDIRECTIONAL);
  _canWrite = true;
 
@@ -170,15 +178,6 @@ internal MsQuicStream(MsQuicConnection.State connectionState, QUIC_STREAM_OPEN_F
  throw;
  }
 
- if (!connectionState.TryAddStream(this))
- {
- _state.Handle?.Dispose();
- _state.StateGCHandle.Free();
- throw new ObjectDisposedException(nameof(QuicConnection));
- }
-
- _state.ConnectionState = connectionState;
-
  _state.TraceId = MsQuicTraceHelper.GetTraceId(_state.Handle);
  if (NetEventSource.Log.IsEnabled())
  {