Return correct error upon websocket message read failure

This fixes variable passed as error reason upon websocker message read failure.
Previously a wrong variable was passed resulting in returning failure with nil error reason.

staging/src/k8s.io/client-go/tools/remotecommand/websocket.go

@@ -312,7 +312,7 @@ func (c *wsStreamCreator) readDemuxLoop(bufferSize int, period time.Duration, de
 				if errRead == io.EOF {
 					break
 				}
-				c.closeAllStreamReaders(fmt.Errorf("read message: %w", err))
+				c.closeAllStreamReaders(fmt.Errorf("read message: %w", errRead))
 				return
 			}
 		}