In my world the difficulty was easy, but I entered the command: / gamerule doMobSpawning false. One day I came to a swamp hut and all of a sudden invisible creature appeared and threw me with splash potions, which almost killed me.

What I expected to happen was...:
I wanted to take a leisurely walk away from the swamp hut and continue collecting sugar cane.

What actually happened was...:
Instead of collecting sugar cane, I was attacked by an invisible creature that poisoned me and almost killed me