Why is this an issue?
If an alternative in a regular expression only matches things that are already matched by another alternative, that alternative is redundant and
serves no purpose.
In the best case this means that the offending subpattern is merely redundant and should be removed. In the worst case it’s a sign that this regex
does not match what it was intended to match and should be reworked.
Noncompliant code example
"[ab]|a" // The "|a" is redundant because "[ab]" already matches "a"
".*|a" // .* matches everything, so any other alternative is redundant