Installation prompt article has a demo page with an error in json, rendering it broken

[azivkovi]

On https://web.dev/learn/pwa/installation-prompt/ there is a link to https://mlearn-pwa-web-app-manifest-promotional.glitch.me/ where a demo of PWA prompt should appear. It doesn't because of an error in manifest.json. From console:

Error: Parse error on line 34: ...s": "512x512", } ], } ----------------------^ Expecting 'STRING', got '}'

Problem appears to be a trailing comma.