Reproduction steps:
1. Open attached project "UnreachableCodeWarning"
2. Notice warning in the console "Unreachable code detected"

Notes:
1. Replacing for loop with foreach loop prevents the warning
2. Function listed below produces Unreachable code warning:

private RaycastHit? RaycastPrefab(Vector3 pnt, float maxDistance, ref float offset)
{
RaycastHit[] hits = Physics.RaycastAll(this.transform.position, pnt.normalized, maxDistance, Physics.kDefaultRaycastLayers);
for (int i = 0; i < hits.Length; i++)
{
return hits[i];
}
return null;
}