I wanted to try staging.vuejs

SPEC

Node : v12.13.0

@vue/cli : v4.5.15

CodePudding user response：

The error is because your Node version simply doesn't know what ?? means.

The ?? is a null coalescing operator. Looking at the MDN docs for ??, you can see at the bottom that support for it was only added in Node 14.0. You're using Node v12.13.

There is really no other solution than to upgrade. I advice you to upgrade to the latest LTS version, which as of this writing is 16.