checks: 0
WITHOUT Null Object · lookup may return null latte · $10.00
Checkout code one line
Checkout lane
swipe a card…
lookupCustomer(card) →
$10.00→—
💥 NullPointerException
One line, two kinds of customer
Swipe 💳 Member card, then 🪪 No card, and watch what null does to the chain.
▸ The code line never changes between worlds — only what lookupCustomer returns does.