panic (overflow) in amount_pico_btc

[mikedilger]

thread '<unnamed>' panicked at /home/mike/.cargo/registry/src/index.crates.io-6f17d22bba15001f/lightning-invoice-0.30.0/src/lib.rs:1081:13:
attempt to multiply with overflow

Could use overflowing_mul() to detect and return None

Panics upstream downstream project, which I cannot catch and swallow.

[mikedilger]

This is probably too verbose but:

pub fn amount_pico_btc(&self) -> Option<u64> {
        match self.hrp.raw_amount {
            None => None,
            Some(v) => {
                let (product, overflow) = v.overflowing_mul(
                    self.hrp
                        .si_prefix
                        .as_ref()
                        .map_or(1_000_000_000_000, |si| { si.multiplier() })
                );
                if overflow {
                    None
                } else {
                    Some(product)
                }
            }
        }
}

I'm not sure if None is acceptable here or it needs refactoring into a Result.