调整

public/react/src/modules/courses/coursesDetail/CoursesLeftNav.js

@@ -682,18 +682,22 @@ class Coursesleftnav extends Component{
 
    if(result.source.droppableId==="shixun_homework"||result.source.droppableId==="graduation"||result.source.droppableId==="attachment"){
 
-     let url ="/course_second_categories/"+result.draggableId+"/move_category.json"
-     this.droppablepost(url,result.destination.index+1)
-
+     let url ="/course_second_categories/"+result.draggableId+"/move_category.json";
+		 if(result.destination.index!=null){
+			 this.droppablepost(url,result.destination.index+1)
+		 }
    }else if(result.source.droppableId==="board"){
 
-     let url ="/boards/"+result.draggableId+"/move_category.json"
-     this.droppablepost(url,result.destination.index+1)
-
+     let url ="/boards/"+result.draggableId+"/move_category.json";
+		 if(result.destination.index!=null) {
+			 this.droppablepost(url, result.destination.index + 1)
+		 }
    }else if(result.source.droppableId==="course_group"){
 			if(result.draggableId!=1){
-				let url ="/course_groups/"+result.draggableId+"/move_category.json"
-				this.droppablepost(url,result.destination.index+1)
+				let url ="/course_groups/"+result.draggableId+"/move_category.json";
+				if(result.destination.index!=null) {
+					this.droppablepost(url, result.destination.index + 1)
+				}
 			}
    }