Don't show the renderer problems to the user in published material

I believe this code is problematic:

• The content looks broken, even if it would be OK without formatting
• The readers are asked to take an action without knowing whether it has already been done
• The staff gets notified manually even though there is already code to detect that something is broken

Instead I propose:

1. Do not display the error message in the finalized content (probably OK to do in the preview)
2. If desired generate a notification to the staff when an error occurs (or just store it in a database).