When does a rules check return 'zero' versus 'null' when a target is no longer legal or information is unavailable?

Ruling: When a target is no longer legal or information is unavailable, the check returns null (not zero). The updated Comprehensive Rules Document will be changed so it is always null when the target is no longer legal.

Nuances:

• Previous examples in the rules incorrectly showed numerical values like Might returning 0, but these will be corrected to null
• For effects like Baited Hook that reference "the killed unit," if no unit was actually killed, there is no unit to check values from, resulting in null
• The distinction matters because null means the value cannot be evaluated at all (preventing further resolution), while 0 would be a valid numerical value that could be used