return errors from jail

src/jail.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"github.com/robertkrimen/otto"
+	"fmt"
 )
 
 var statusJs string
@@ -11,25 +12,45 @@ func Init(js string) {
 	statusJs = js
 }
 
+func printResult(res string, err error) string {
+	var out string
+	if err != nil {
+		out = fmt.Sprintf(`{
+		        "error": %s
+		        }`,
+			err.Error())
+	} else {
+		out = fmt.Sprintf(`{
+		        "result": %s
+		        }`,
+			res)
+	}
+
+	return out
+}
+
 func Parse(chatId string, js string) string {
 	vm := otto.New()
 	jjs := statusJs + js + `
 	var catalog = JSON.stringify(_status_catalog);
 	`
 	vms[chatId] = vm
-	vm.Run(jjs)
+	_, err := vm.Run(jjs)
 	res, _ := vm.Get("catalog")
+	err.Error()
 
-	return res.String()
+	return printResult(res.String(), err)
 }
 
 func Call(chatId string, path string, args string) string {
 	vm, ok := vms[chatId]
 	if !ok {
-		return ""
+		return fmt.Sprintf(
+			"{\"error\":\"Vm[%s] doesn't exist.\"}",
+			chatId)
 	}
 
-	res, _ := vm.Call("call", nil, path, args)
+	res, err := vm.Call("call", nil, path, args)
 
-	return res.String()
+	return printResult(res.String(), err);
 }