luci-mod-freifunk: calling via "Freifunk" button on page-bottom raises a lua-error

With recent LuCI (master branch; somewhere before https://github.com/openwrt/luci/commit/09a3b4730a769c43067ff1fb3e4aad339271fbc3) Luci throws an error when clicking on the "Freifunk" button. The button on the page-bottom, beside the "Administration" button.

> /usr/lib/lua/luci/dispatcher.lua:1190: attempt to index local 'f' (a nil value)
stack traceback:
/usr/lib/lua/luci/dispatcher.lua:1190: in function 'createtree_json'
/usr/lib/lua/luci/dispatcher.lua:703: in function 'menu_json'
/usr/lib/lua/luci/dispatcher.lua:796: in function 'dispatch'
/usr/lib/lua/luci/dispatcher.lua:995: in function 'dispatch'
/usr/lib/lua/luci/dispatcher.lua:479: in function

Seen with 05760f09e294caee423613ab681ce10d48629a19. Calling http:///cgi-bin/luci/ works fine, calling http:///cgi-bin/luci/freifunk fails.