Default podcast platform icon is broken

Describe the bug

Default podcast platform icon is broken on the pblic website (but ok on the admin one).

Steps to reproduce

1. Create a podcast
2. Add a platform with default icon (eg. Curiocaster)
3. Go to the public website

Expected behavior

Default icon should be displayed.

Actual behavior

Tofu is shown instead.

Relevant logs and/or screenshots

Context

• Castopod: 1.0.0-beta.9
• OS: Debian 10
• Browser: Any
• Web server: Nginx

Possible fixes

?