Undefined offset: 4 in _menu_translate()

With Relation enabled and in use, Relation UI module disabled, and Conditional Fields module enabled (and used elsewhere but not on the relation), accessing /admin/structure triggers the watchdog notice "Undefined offset: 4 in _menu_translate() (line 791 of /.../htdocs/includes/menu.inc)."

My guess is that Conditional Fields is looking for fields that might have conditional dependencies, and it sees fields on the relation and can't figure out how to manage them. In this case, _menu_translate() stumbles on not having any way to handle path "/admin/structure/relation/manage/%/dependencies".

I do not have the expertise to determine if this actually is a problem with Conditional Fields (related issue #2644867 has collected a couple of these), or if it's simply exposing an existing problem, and it's the responsibility other modules to clean up their interfaces.

In case it's the latter, the patch in comment 1 suppresses the warning by providing a menu item that leads nowhere unless relation_ui is enabled. A slightly better approach might be a page or callback that explains the actual problem (or at least logs something meaningful), but it seemed like a little expert guidance on a solution that's Drupalish and consistent with the rest of Relation could save a lot of effort.