cmds2: handle error return codes

cmd/ipfs2/main.go

@@ -150,6 +150,10 @@ func (i *cmdInvocation) Run() (output io.Reader, err error) {
 		return nil, err
 	}
 
+	if err := res.Error(); err != nil {
+		return nil, err
+	}
+
 	return res.Reader()
 }
 

commands/response.go

@@ -117,6 +117,11 @@ func (r *response) Marshal() ([]byte, error) {
 	}
 	encType := EncodingType(strings.ToLower(enc))
 
+	// Special case: if text encoding and an error, just print it out.
+	if encType == Text && r.Error() != nil {
+		return []byte(r.Error().Error()), nil
+	}
+
 	var marshaller Marshaller
 	if r.req.Command() != nil && r.req.Command().Marshallers != nil {
 		marshaller = r.req.Command().Marshallers[encType]