Why does electron swear on es6?

Question

JavaScript

Some strange thing with this electron js.
I'm trying to write my js file in es6, which is why I chose electron instead of nw.
So if you start the project with the electron command. (I have it globally installed) then everything is OK, everything works without errors, but if you run the same project but through npm start , then the application starts but swears at let, const ... and arrow functions. The same problem if you build applications through electron-packager . and run the already compiled application.
How can I fix this?