Web App - display error: "fullscreen"

I do not know if it's canary's fault, but when I add this function to my PWA, it looks like this:

Hereisthecode:

{"short_name": "EAOS",
"name": "EduApps Operating System",
"display": "fullscreen",
"background_color": "#333",
"icons": [
  {
    "src": "favicon.png",
    "type": "image/png",
    "sizes": "128x128"
  }
],
"start_url": "/index.html"
}