Violated LSP with strengthened precondition

class Account { withdraw(amount: number): void { // allows amount >= 0 } } class PremiumAccount extends Account { withdraw(amount: number): void { if (amount < 100) throw new Error('min 100'); // ... } } // client code: function drain(a: Account, amt: number) { a.withdraw(amt); } drain(new PremiumAccount(), 20); // throws Which principle is violated and why?