Adorable little game! Some polish is to be expected. Yes sorry to say that my screen also turned black at some point after beating the boss but I'm glad you posted the ending!
The music is great, the art is lovely and the mechanic of defeating the ant(s) with jumping into (onto) it is clever and fun. Think there should be an option to turn down volume. Some jump sfx for the player would be nice as there are sfx for other things like text, smashing, doors opening, and squashing.