When the last remote is removed on a system that has tearoff menu items
the code that adjusts the fetch and prune menus may raise an error when
probing the menu entry for a non-existing -label option.
Check the entry type to avoid this fault.
Reported-by: Vedran Miletić <rivanvx@gmail.com> Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>