when run npm start, missing start

Question

Working on my new android app, but when i try to start the server i get.

npm ERR! missing script: start npm ERR! A complete log of this run can be found in: npm ERR!
/home/.npm/_logs/2018-09-05T23_17_23_146Z-debug.log

I use npm version 6.1.0

my package.json

{
  "name": "ionic-hello-world",
  "author": "xxxxxxxxxxxxxxx",
  "homepage": "xxxxxxxxxxxxx",
  "private": true,
  "scripts": {
    "clean": "ionic-app-scripts clean",
    "build": "ionic-app-scripts build",
    "ionic:build": "ionic-app-scripts build",
    "ionic:serve": "ionic-app-scripts serve"
  },

I hope somone can help me.