优化 index-tree.vue.vm 文件，undefined 修改为 null

fungleo

2020-07-26 ca657b048275fbac4fd13e3c26808ad20e8ea128

 ruoyi-ui/src/assets/styles/element-variables.scss

@@ -6,7 +6,7 @@
/* theme color */

$--color-primary: #1890ff;

$--color-success: #13ce66;

$--color-warning: #FFBA00;

$--color-warning: #ffba00;

$--color-danger: #ff4949;

// $--color-info: #1E1E1E;