miral-shell crashes during shutdown

Running lp:miral on Zesty/Mir0.26.1.

    $ bin/miral-shell --x11-displays 1200x900 --window-management-trace --startup gnome-terminal

After experimenting with bug 1668467 (trying to open the gnome-calculator preferences multiple times) on exiting the server I saw an error:

[2017-02-28 14:58:10.474959] mirserver: Stopping
[2017-02-28 14:58:10.475325] <WARNING> miral::Window Management: info_for throws ERROR: Dynamic exception type: std::out_of_range
std::exception::what: map::at

[2017-02-28 14:58:10.475432] <WARNING> miral::Window Management: place_new_window throws ERROR: Dynamic exception type: std::out_of_range
std::exception::what: map::at

[2017-02-28 14:58:10.476431] miral::Window Management: advise_delete_window window_info={name=wallpaper, type=gloss, state=fullscreen, restore_rect=((0, 0), (1200, 900)), children={}, min_width=0, min_height=0, max_width=2147483647, max_height=2147483647, width_inc=1, height_inc=1, min_aspect={0, 4294967295}, max_aspect={4294967295, 0}, preferred_orientation=15, confine_pointer=0, output_id=1}
[2017-02-28 14:58:10.476528] miral::Window Management: advise_delete_app application={application=decorations, windows={}}

Process finished with exit code 1