Error while trying to use the following icon from the Manifest

Why is the devtools in Chrome showing this error for all my apps?

Error while trying to use the following icon from the Manifest: 
https://<appname>.anvil.app/_/theme/favicon-32x32.ico 
(Resource size is not correct - typo in the Manifest?)

The icon’s URL is the one I set in the apps by clicking on the Change image button on the Settings - General page.