Why your Midnight contract "can't be found on chain" (or: Midnight, stop playing with my emotions)

I'm a self-taught learner grinding through the Midnight quests, and this week the chain and I had a little falling out. I deployed a contract, got an address back, submitted it like a proud parent at a recital, and got served four of the saddest words in Web3: "cannot find contract on chain." My cod