Proof of execution

Debug this JavaScript function and explain the bug:

function addPrices(items) {
  return items.reduce((sum, item) => {
    sum + item.price;
  }, 0);
}

Input:
[{ price: 10 }, { price: 15 }, { price: 5 }]

Expected result: 30
Actual result: undefined

The bug is here:

```js
return items.reduce((sum, item) => {
    sum + item.price;   // !!!
}, 0);
```

(See: arrow function with block body, implicit return, what `reduce` does with the callback result.)

What happens:

- The `{ ... }` turns the arrow into a statement block, not an expression.
- `sum + item.price;` evaluates the sum but then throws the value away.
- No `return`, so the callback returns `undefined`.
- First iteration: accumulator becomes `undefined`.
- Subsequent iterations: `un…

{
  "success": true,
  "transaction": "0xde2a953507ea47a9203da520340c4a66b1114888a0086f515e74fdabf83df30b",
  "network": "eip155:8453"
}