diff --git a/core/otto.go b/core/otto.go
index c4921f5..11cc5ea 100644
--- a/core/otto.go
+++ b/core/otto.go
@@ -146,11 +146,11 @@ func init() {
 			vm.Set("push", push)
 			vm.Set("sendText", func(call otto.Value) interface{} {
 				s.Reply(call.String())
-				return nil
+				return otto.Value{}
 			})
 			vm.Set("sendImage", func(call otto.Value) interface{} {
 				s.Reply(ImageUrl(call.String()))
-				return nil
+				return otto.Value{}
 			})
 			rt, err := vm.Run(template + `
 ""