manifest does not contain a suitable icon

Provide the steps to reproduce

1. Run LH on https://tietracker.com

What is the current behavior?

Lighthouse displays following error regarding the manifest:

Manifest does not contain a suitable icon - PNG, SVG or WebP format of at least 144 px is required, the sizes attribute must be set, and the purpose attribute, if set, must include “any” or “maskable”.

No supplied icon is at least 144 px square in PNG, SVG or WebP format

Manifest which looks like following and does seem to match expected above description:

{
  "name": "Tie Tracker",
  "short_name": "Tie Tracker",
  "icons": [
    {
      "purpose": "maskable",
      "src": "/assets/favicon/android-chrome-192x192.png",
      "sizes": "192x192",
      "type": "image/png"
    },
    {
      "purpose": "maskable",
      "src": "/assets/favicon/android-chrome-512x512.png",
      "sizes": "512x512",
      "type": "image/png"
    }
  ],
  "start_url": "/",
  "display": "standalone",
  "theme_color": "#230f29",
  "background_color": "#ffffff"
}

What is the expected behavior?

Either it is an error and the icons of the manifest should be recognized as valid or, the description should be improved to display what’s missing.

Environment Information

• Chrome version: v91

Screenshot

[phoglenix]

The issue (see chromium bug linked above) is now fixed at head. It should appear in Chrome 93. I split the message into two separate warnings (one for “you only have maskable icons”, one for “avoid having any maskable icons”)

[adamraine]

So setting the pattern of "any maskable" is discouraged but not required. Unfortunatley, the difference between “must not” and “should not” is a bit subtle in the applications panel message.

The Lighthouse message is now correct, but we removed the part discouraging "any maskable" https://github.com/GoogleChrome/lighthouse/pull/12678#discussion_r655596372.

gelnrob@ is open to changing the message, so we can reevaluate what we want to include if that happens.