Error in setStat() when toShow is nil

I get this error when leveling skills:

I think it should look like this:

-- in function setStat()
if toShow ~= nil then
  ui.showMessage(L(toShow, {attr=statName, value=value}))
end

(OpenMW git changeset 964f288c138867a3e772dc1bee84afe6fb88ae92)