vue项目VUE启动报错：Error: The project seems to require yarn but it‘s not installed

VUE启动报错：Error: The project seems to require yarn but it‘s not installed：

出现这个原因的话，如果在项目里面是因为项目中存在yarn.lock

只需要把yarn.lock在该项目删除

然后全局安装就好了

npm install -g yarn