bug#27334: 25.2; `C-h k mouse-3' on mode line raises error

[Drew Adams]

emacs -Q

C-h k

Right-click `mouse-3' on the mode line, in an area where there is no
text.  This error is raised:

byte-code: Args out of range: "Describe key (or click or menu item):
mouse-3", 0, 62

This is a regression from Emacs 24.5.  It started with Emacs 25.1.


In GNU Emacs 25.2.1 (x86_64-w64-mingw32)
 of 2017-04-24 built on LAPHROAIG
Windowing system distributor 'Microsoft Corp.', version 6.1.7601
Configured using:
 'configure --without-dbus --without-compress-install 'CFLAGS=-O2
 -static -g3''