Improve batch blame midpoint

src/proof.rs

@@ -410,14 +410,20 @@ impl Proof {
  let mut right = proofs.len();
 
  while left < right {
- let unscaled_average = left
- .checked_add(right)
+ #[allow(clippy::arithmetic_side_effects)]
+ let average = left
+ .checked_add(
+ // This cannot underflow since `left < right`
+ (right - left) / 2,
+ )
  .ok_or(ProofError::FailedBatchVerificationWithSingleBlame { index: None })?;
 
- let mid = if unscaled_average % 2 == 0 {
- unscaled_average / 2
+ #[allow(clippy::arithmetic_side_effects)]
+ // This cannot underflow since `left < right`
+ let mid = if (right - left) % 2 == 0 {
+ average
  } else {
- (unscaled_average / 2)
+ average
  .checked_add(1)
  .ok_or(ProofError::FailedBatchVerificationWithSingleBlame { index: None })?
  };