Extension emulator does not show icons or placeholders

[puf]

Describe the bug

After installing an extension in the emulator, it shows up on http://127.0.0.1:4000/extensions/storage-firestore-sync as:

Expected behavior

If the extension has an icon, the emulator should show that - as extensions.dev does.
If the extension doesn't have an icon, the emulator should show a placeholder - as extensions.dev does.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: macOS (Ventura 13.3.1)
• Browser: Chrome (113.0.5672.126)