What's the noun for humourlessness? Here's the word you're looking for.
humour
(uncountable) The quality of being amusing, comical, funny. [from the early 18th c.]
(uncountable) A mood, especially a bad mood; a temporary state of mind or disposition brought upon by an event; an abrupt illogical inclination or whim.
(archaic or historical) Any of the fluids in an animal body, especially the four "cardinal humours" of blood, yellow bile, black bile and phlegm that were believed to control the health and mood of the human body.