fix lint errors

app/proxyman/mux/mux.go

@@ -133,8 +133,8 @@ func (m *Client) monitor() {
 		select {
 		case <-m.done.Wait():
 			m.sessionManager.Close()
-			common.Close(m.link.Writer)
-			pipe.CloseError(m.link.Reader)
+			common.Close(m.link.Writer)    // nolint: errcheck
+			pipe.CloseError(m.link.Reader) // nolint: errcheck
 			return
 		case <-timer.C:
 			size := m.sessionManager.Size()
@@ -167,14 +167,15 @@ func fetchInput(ctx context.Context, s *Session, output buf.Writer) {
 	}
 	s.transferType = transferType
 	writer := NewWriter(s.ID, dest, output, transferType)
-	defer s.Close()
-	defer writer.Close()
+	defer s.Close()      // nolint: errcheck
+	defer writer.Close() // nolint: errcheck
 
 	newError("dispatching request to ", dest).WithContext(ctx).WriteToLog()
 	if pReader, ok := s.input.(*pipe.Reader); ok {
 		if err := copyFirstPayload(pReader, writer); err != nil {
 			newError("failed to fetch first payload").Base(err).WithContext(ctx).WriteToLog()
 			writer.hasError = true
+			pipe.CloseError(s.input)
 			return
 		}
 	}
@@ -182,6 +183,7 @@ func fetchInput(ctx context.Context, s *Session, output buf.Writer) {
 	if err := buf.Copy(s.input, writer); err != nil {
 		newError("failed to fetch all input").Base(err).WithContext(ctx).WriteToLog()
 		writer.hasError = true
+		pipe.CloseError(s.input)
 		return
 	}
 }

app/proxyman/mux/session.go

@@ -118,8 +118,8 @@ func (m *SessionManager) Close() error {
 	m.closed = true
 
 	for _, s := range m.sessions {
-		common.Close(s.input)
-		common.Close(s.output)
+		common.Close(s.input)  // nolint: errcheck
+		common.Close(s.output) // nolint: errcheck
 	}
 
 	m.sessions = nil
@@ -137,8 +137,8 @@ type Session struct {
 
 // Close closes all resources associated with this session.
 func (s *Session) Close() error {
-	common.Close(s.output)
-	common.Close(s.input)
+	common.Close(s.output) // nolint: errcheck
+	common.Close(s.input)  // nolint: errcheck
 	s.parent.Remove(s.ID)
 	return nil
 }

app/proxyman/mux/writer.go

@@ -102,6 +102,7 @@ func (w *Writer) WriteMultiBuffer(mb buf.MultiBuffer) error {
 	return nil
 }
 
+// Close implements common.Closable.
 func (w *Writer) Close() error {
 	meta := FrameMetadata{
 		SessionID:     w.id,
@@ -114,6 +115,6 @@ func (w *Writer) Close() error {
 	frame := buf.New()
 	common.Must(meta.WriteTo(frame))
 
-	w.writer.WriteMultiBuffer(buf.NewMultiBufferValue(frame))
+	w.writer.WriteMultiBuffer(buf.NewMultiBufferValue(frame)) // nolint: errcheck
 	return nil
 }