Task: Fix Cart Quantity Bug

Fix Cart Quantity Bug

Objective

Fix the bug in the cart where product quantity can reach 0 or become negative.

Why It Matters

A quantity of 0 or less makes no logical sense and can cause calculation errors. This teaches defensive programming and input validation.

Technical Requirements

• Modify updateQuantity in src/features/cart/useCartStore.js
• Add a minimum quantity check: if newQuantity < 1, either:
  • Clamp to 1 (prevent going below), OR
  • Remove the item from the cart
• Ensure the UI reflects this constraint properly

Expected Behavior

• Clicking "−" when quantity is 1 either keeps it at 1 or removes the item
• Quantity never displays as 0 or negative
• The total price calculation remains correct

Acceptance Criteria

• Quantity cannot go below 1
• Decided behavior for quantity at 1 (clamp or remove)
• Total price is always correct
• UI buttons disabled or provide feedback at minimum quantity

Edge Cases

• Rapid clicking of the "−" button
• Direct quantity input (if implemented later)
• Cart with multiple items at quantity 1

Hints

• Add if (newQuantity < 1) return; before the state update, or
• Add if (newQuantity < 1) { removeFromCart(productId); return; }
• Consider disabling the "−" button in the UI when quantity is 1