commands: Made Request#Option also return an existence bool

commands/request.go

@@ -21,8 +21,9 @@ func (r *Request) SetPath(path []string) {
 	r.path = path
 }
 
-func (r *Request) Option(name string) interface{} {
-	return r.options[name]
+func (r *Request) Option(name string) (interface{}, bool) {
+	val, ok := r.options[name]
+	return val, ok
 }
 
 func (r *Request) SetOption(name string, value interface{}) {

commands/response.go

@@ -57,8 +57,8 @@ func (r *Response) Marshal() ([]byte, error) {
 		return nil, fmt.Errorf("No error or value set, there is nothing to marshal")
 	}
 
-	enc := r.req.Option("enc")
-	if enc == nil {
+	enc, ok := r.req.Option("enc")
+	if !ok || enc.(string) == "" {
 		return nil, fmt.Errorf("No encoding type was specified")
 	}
 	encType := EncodingType(strings.ToLower(enc.(string)))