App tile: Discussion is show even if plone.app.discussion is not installed. #651
Description
When customizing a Mosaic layout in the App category the 'Discussion' tile is available whether plone.app.discussion is installed or not.
In a website without plone.app.discussion installed, when customizing the Mosaic layout, the Discussion tile is always available in the "Insert" menu. After clicking the tile a default popup appears saying it's not found.
Expected behavior
In Plone 6.1 plone.app.discussion has become optional, so one should not rely on it being available, but test for it's presence first. When plone.app.discussion is not installed, the tile should not appear in the 'Insert' menu.
Probably add a line similar to this in the zcml:
zcml:condition="installed plone.app.discussion"
Screenshots
Software (please complete the following information):
- Plone Version 6.1.0.
Additional context
Add any other context about the problem here.