Problem/Motivation
After installing and uninstalling the navigation
module, issues are raised by some contrib projects with the `navigation` theme hook not found.
Steps to reproduce
* Install fresh D11 on minimal profile
* Install the navigation module
* Add drupal/gin and drupal/gin_toolbar
* Install the Gin theme + enable gin_toolbar
* In theme settings, select "Show Secondary Toolbar in Frontend"
* Save and go to front page
* Result: the secondary toolbar is not displayed on front
This is the warning message logged by the ThemeManager:
Theme hook navigation not found
Proposed resolution
TBD
Remaining tasks
* Identify where is the navigation theme hook declared / override by the navigation
module
* Fix the situation on module uninstall (?)