Tracing: coins.cpp:102:22: error: 'coin' used after it was moved [bugprone-use-after-move]

This may be fine because `int` values aren't touched by a `std::move`, but it seems brittle and confusing:

```
coins.cpp:102:22: error: 'coin' used after it was moved [bugprone-use-after-move,-warnings-as-errors]
           (uint32_t)coin.nHeight,
                     ^
coins.cpp:96:21: note: move occurred here
    it->second.coin = std::move(coin);
                    ^
```

