knockout format: error message in ranking

In knockout competition format:

When one of the competitors in a match is ‘unknown’ (= bye), an ‘undefined offset’ error occurs. This happens when the match result is empty.

Result must be ‘bye’ to fix the error.

Proposed fix: enforce that the result is ‘bye’ when one of the competitors does not exist.

https://ww.wp.xz.cn/plugins/sports-club-management/