legacy: correctly handle errors

command.go

@@ -70,9 +70,14 @@ var ErrIncorrectType = errors.New("The command returned a value with a different
 // Call invokes the command for the given Request
 func (c *Command) Call(req Request, re ResponseEmitter) (err error) {
 	// we need the named return parameter so we can change the value from defer()
-	defer re.Close()
+	defer func() {
+		if err == nil {
+			re.Close()
+		}
+	}()
 
-	cmd, err := c.Get(req.Path())
+	var cmd *Command
+	cmd, err = c.Get(req.Path())
 	if err != nil {
 		return err
 	}

legacy.go

@@ -63,8 +63,7 @@ func (rw *responseWrapper) Output() interface{} {
 
 					if err == io.EOF || err == context.Canceled {
 						return
-					}
-					if err != nil {
+					} else if err != nil {
 						log.Error(err)
 						return
 					}
@@ -403,9 +402,21 @@ func NewCommand(oldcmd *oldcmds.Command) *Command {
 			errCh := make(chan error)
 			go res.Send(errCh)
 			oldcmd.Run(oldReq, res)
-			err := <-errCh
-			if err != nil {
-				log.Error(err)
+			select {
+			case err := <-errCh:
+				if err != nil {
+					if e, ok := err.(*cmdkit.Error); ok {
+						err = *e
+					}
+
+					if e, ok := err.(cmdkit.Error); ok {
+						re.SetError(e.Message, e.Code)
+					} else {
+						re.SetError(err.Error(), cmdkit.ErrNormal)
+					}
+				}
+			case <-req.Context().Done():
+				re.SetError(req.Context().Err(), cmdkit.ErrNormal)
 			}
 		}
 	}

legacy_test.go

@@ -2,6 +2,7 @@ package cmds
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io"
 	"testing"
@@ -57,6 +58,10 @@ func TestNewCommand(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	req.SetRootContext(ctx)
+
 	buf := bytes.NewBuffer(nil)
 
 	testCmd := root.Subcommand("test")