get_chat_by_id sent admins down a branch that returned the chat only when
ENABLE_ADMIN_CHAT_ACCESS was on, or the chat was internal, and never fell
through to the access-grant and shared-folder checks. With the setting off,
an admin was therefore denied a chat that had been deliberately shared with
them, either directly or through a shared folder, while any non-admin holding
the same grant could open it. The admin role removed access the user had been
given rather than only closing the admin-only path.
Try the admin path first, then let everyone fall through to the grant and
folder checks. ENABLE_ADMIN_CHAT_ACCESS=false still closes the admin-only
route to other users' chats, and internal chats stay reachable.
Classic298
a35b37adcd