`write_to_prefix` generates panic path

The `write_to_prefix` function is generating a panic path in our code, and I am pretty sure it is the `bytes[..size].copy_from_slice(self.as_bytes());` line. The compiler doesn't have enough information to elide the slice comparison check.

If the code was written like the following, the compiler should not generate a panic path

```rust
fn write_to_prefix(&self, mut bytes: B) -> Option<()> {
let source = self.as_bytes();
if bytes.len() < source.len() {
return None;
}

bytes[..size].copy_from_slice(source);
Some(())
}

```