Currently, if an extension inspector is closed while there is an error in the generated content, the last valid rendering remains, with no visible prompt that there is an error until after the page is saved. The only reason for not rendering an error while the inspector is open is to prevent the inspector from jumping around. So errors should be rendered once the inspector is closed.
Related Gerrit Patches:
|mediawiki/extensions/VisualEditor : master||Ensure full error message is shown when inspector is closed|
|VisualEditor/VisualEditor : master||Pass staging state through Document#commit to ve.dm.Node update event|