FORCDK-MENU-006
Thrown by forty-cdk/menu.
[forty-cdk/menu] FORCDK-MENU-006: [forMenuSub] must be used inside a [forDropdownMenu], [forContextMenu], or another [forMenuSub] element.
Cause
No FOR_MENU_CONTEXT provider is visible from [forMenuSub]. Angular resolves a directive's dependencies at the template's declaration site rather than where it is stamped, so a piece declared in an ng-template outside the root resolves nothing even when it renders inside it.
Fix
Move [forMenuSub] inside a [forDropdownMenu], [forContextMenu], or another [forMenuSub] element, declaring any ng-template it lives in there too.