From f214e741b7977ce9e663706b4195cd9a024a52a1 Mon Sep 17 00:00:00 2001
From: hjm <63528605@qq.com>
Date: Mon, 12 Aug 2019 18:31:50 +0800
Subject: [PATCH] del

---
 public/react/src/modules/courses/exercise/new/NullEditor.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/public/react/src/modules/courses/exercise/new/NullEditor.js b/public/react/src/modules/courses/exercise/new/NullEditor.js
index 8cfb21a5f..9a99a067d 100644
--- a/public/react/src/modules/courses/exercise/new/NullEditor.js
+++ b/public/react/src/modules/courses/exercise/new/NullEditor.js
@@ -196,12 +196,14 @@ class NullEditor extends Component{
   }
   
   onAnswerChange = (index, itemIndex, val) => {
+    if (this.state.standard_answers[index]) {
     this.setState(
         (prevState) => ({ 
           standard_answers : update(prevState.standard_answers
             , {[index]: {$splice: [[itemIndex, 1, val]]}}),
         })
       )
+    }
   }
   addChildAnswer = (index) => {
     this.setState(