be less twitchy about errors from Read that happen once we've already burned the pipe

StackExchange.Redis/ConnectionMultiplexer.cs

@@ -155,8 +155,8 @@ internal void OnInternalError(Exception exception, EndPoint endpoint = null, Con
         {
             try
             {
-                Trace("Internal error: " + origin + ", " + exception == null ? "unknown" : exception.Message);
                 if (_isDisposed) return;
+                Trace("Internal error: " + origin + ", " + exception == null ? "unknown" : exception.Message);
                 var handler = InternalError;
                 if (handler != null)
                 {

StackExchange.Redis/PhysicalConnection.cs

@@ -1274,9 +1274,9 @@ private void OnDebugAbort()
 
         private async void ReadFromPipe() // yes it is an async void; deal with it!
         {
+            bool allowSyncRead = true, isReading = false;
             try
             {
-                bool allowSyncRead = true;
                 while (true)
                 {
                     var input = _ioPipe?.Input;
@@ -1284,10 +1284,12 @@ private void OnDebugAbort()
 
                     // note: TryRead will give us back the same buffer in a tight loop
                     // - so: only use that if we're making progress
+                    isReading = true;
                     if (!(allowSyncRead && input.TryRead(out var readResult)))
                     {
                         readResult = await input.ReadAsync().ForAwait();
                     }
+                    isReading = false;
 
                     var buffer = readResult.Buffer;
                     int handled = 0;
@@ -1310,11 +1312,21 @@ private void OnDebugAbort()
                 RecordConnectionFailed(ConnectionFailureType.SocketClosed);
             }
             catch (Exception ex)
+            {
+                // this CEX is just a hardcore "seriously, read the actual value" - there's no
+                // convenient "Thread.VolatileRead<T>(ref T field) where T : class", and I don't
+                // want to make the field volatile just for this one place that needs it
+                if (isReading && Interlocked.CompareExchange(ref _ioPipe, null, null) == null)
+                {
+                    // yeah, that's fine... don't worry about it
+                }
+                else
                 {
                     Trace("Faulted");
                     RecordConnectionFailed(ConnectionFailureType.InternalFailure, ex);
                 }
             }
+        }
 
         private int ProcessBuffer(ref ReadOnlySequence<byte> buffer)
         {