Pressing the RQM button on the hotbar resulted in this error.

The mod Awesome Research Queue Manager (1.3.7) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event awesome-rqm::on_lua_shortcut (ID 42)
awesome-rqm/view/gui/gutil.lua:82: attempt to concatenate a nil value
stack traceback:
awesome-rqm/view/gui/gutil.lua:82: in function 'get_tooltip_text'
awesome-rqm/view/gui/components/tech.lua:22: in function 'get_tech_icon'
awesome-rqm/view/gui/components/tech.lua:287: in function 'populate'
awesome-rqm/view/gui/components.lua:212: in function 'repopulate_dynamic'
awesome-rqm/view/gui/components.lua:219: in function 'repopulate_all'
awesome-rqm/view/gui.lua:25: in function 'open'
awesome-rqm/view/gui.lua:66: in function 'toggle'
awesome-rqm/control.lua:217: in function <awesome-rqm/control.lua:215>

Ay caramba, that's the exact error I hoped to have fixed in 1.3.7.. Turns out I was fixing it in the wrong place. Should be solved in 1.3.8 now

All good here. Thanks for the fix.