less编译时报错

ERROR in ./~/css-loader!./~/postcss-loader/lib!./~/less-loader!./src/components/layer/layer.less

Module build failed: visitors[i].run is not a function

 @ D:\imooc\webpack-demo1\src\components\layer\layer.less (line null, column -1)

 near lines:

        width: 600px;

 @ ./src/components/layer/layer.less 4:14-174