So the error for /mnt/overlay/granite/ui/content/shell/header/actions/pulse.data.json are related to the Notification Inbox, javascript does an update and uses that to pull things that are outstanding for a user. So thats why you are seeing this.
does the path "/etc/workflow/models/dam/approve_asset/jcr:content/model" exist?
I think you have a workflows that is still referencing a deleted workflow model, you could find a delete that workflow and this will go away.
Just to confirm you don't have any running instance when you check http://localhost:4502/libs/cq/workflow/content/console.html
Also are you on AEM6.1 or 6.2? And did you just do an upgrade?