Fix NaN/Infinity handling in responseAdDisplayCount

[pavankumar-vh]

Overview

Fix NaN/Infinity handling in the responseAdDisplayCount function in common/src/util/lazy-response-ads.ts.

Bug Description

The function used Math.floor() without checking if the input was a valid number. If params.eligibleCount or params.poolSize was NaN or Infinity, Math.floor() would return NaN, and Math.max(0, NaN) would return NaN, causing incorrect results.

Fix

Added Number.isFinite() checks to default to 0 for invalid numbers.

Testing

No existing tests for this function, but the fix prevents incorrect behavior with invalid inputs.

Files Changed

• common/src/util/lazy-response-ads.ts - Added NaN/Infinity validation

Scope

This change only touches common/ which is an approved contribution area per the Contributing Guide.

[codebuff-team]

Thanks for the contribution. The change itself is small and correct in isolation: guarding against NaN/Infinity before Math.floor is a sound defensive pattern, and the fix doesn't change behavior for valid finite inputs.

A few things that would make this port-ready:

1. No test coverage. The PR body admits there are no existing tests, but that's an argument for adding one here, not a reason to skip it. A couple of unit tests (responseAdDisplayCount({eligibleCount: NaN, poolSize: 10}), Infinity cases) would make this trivially verifiable and much more likely to be ported as-is.

2. Root cause unclear. The description doesn't establish where these invalid values would actually originate from - is this a real observed bug (e.g. an upstream division by zero producing NaN) or a purely defensive/theoretical fix? If it's theoretical, it's still reasonable, but worth stating plainly rather than implying it fixes an observed incorrect-behavior case.

3. Minor: Infinity for poolSize would already be handled correctly by the existing poolSize >= MAX_RESPONSE_AD_POOL_SIZE check before this fix (since Infinity >= MAX_RESPONSE_AD_POOL_SIZE is true), so the practical risk is mostly around NaN. Worth double-checking which case you actually hit.

Add a small test file exercising these edge cases and this becomes an easy merge.