Oh so I tested it with other orders and the "Incorrect ingredients" only occurs when the order has more than one thing between the buns.
For example: a "bun cheese bun" order works normally but a "bun onion tomato bun" one states I have incorrect/missing ingredients.
Also, one fix I've found for "An exception has occured" is rolling back and keep discarding the items because even though this screen shows up it still discards the item once I restart the mini game and I can get rid of them all one by one patiently.
Viewing post in Rabbits Burn Softly {Week 1} comments
I had this issue too, I can't comment on the error screen, I just had to reload a save, but the burger situation isn't actually a bug, it's just not super clear the order.
When you make the burgers, you put them in order like you're reading them top to bottom. So bun onion cheese bun is the onion below the cheese. Threw me off for a bit, but once I figured that out, the minigame went smoothly.