Since for some time "apex.theme42.toggleWidgets.expandWidget" is deprecated (Thanks Matt Nolan for info).
a workaround is added in docs/searchNavMenu.js library
$('.t-PageBody:not(.js-navExpanded) #t_Button_navControl').click();
Also, like #10 bugfix will be included in the new release coming soon supported from APEX 21.1 version.