What is the correct way to use Grunt?

[Azurepulse]

Hi,I'm new to nodeBB and I was trying to develop on Intellij.
I simply add Configuration for Grunt using the default Grunt.js in the nodeBB folder.
But I noticed something was different between running Grunt and running "nodebb --dev start".
I wrote an empty plugin using "nodebb-plugin-quickstart". It works normal on "nodebb-dev-start".
But,when I use Grunt to run it,it says "warn: [upgrade/appendPluginScripts] Unable to read plugin.json for plugin nodebb-plugin-fr-exam. Skipping." And all the sudden,the empty plugin I modified doesn't work anymore.No settings on ACP , no consoles on pages(I modified from nodebb-plugin-quickstart).
What exactly did I do wrong?
I'm pretty sure the dev group is using Grunt since the building process is annoying.There's no reason I can't use Grunt ,right?Please help.