You should post an issue here on GitHub, so that Ivo (the widget author) can investigate. Looks like possibly a case where a widget library is being imported but the path to that library is incorrect.
Hi Erik,
So you did not have the GoogleMapsCustomMarker widget in your project and never had? Can you tell a bit more about the scenario? I can not replicate this.
Two tips if you do use the widget: Clean the deployment directory and update to the newest version of my GoogleMapsCustomMarker widget. There should not be any dependency with a async file.
[EDIT] : you logged a bug on my widget on GitHub, but you are actually not using my widget as I can see from your other issue with the info bubble parameters. Please contact that developer. I will close the issue on GitHub. Good luck!
Regards,
Ivo