新建，然后删除CD选项，再输入题干，会调用到这里，且index是3

public/react/src/modules/courses/exercise/new/SingleEditor.js

@@ -182,6 +182,10 @@ class SingleEditor extends Component{
     this.setState({ standard_answers })
   }
   onOptionContentChange = (value, index) => {
+    if (index >= this.state.question_choices.length) {
+      // TODO 新建，然后删除CD选项，再输入题干，会调用到这里，且index是3
+      return;
+    }
     let question_choices  = this.state.question_choices.slice(0);    
     question_choices[index] = value;
     this.setState({ question_choices })