Can someone explain "if exists true whose (if true then exists ..."

[brolly33]

I think we talked about this in 2017

Test for existence of an inspector/operator?

Guarded Relevance to the rescue. It will trap the language error where the pipe inspector is not quite clever enough to do so. q: exists true whose ( if true then ( some dodgy expression ) else false ) A: False q: if (exists true whose ( if true then ( exists codename of operating system ) else false )) then (codename of operating system as string ) else (“The relevance does not work on this version/platform of BigFix”) A: The relevance does not work on this version/platform of BigFix q: …

To further expand, the whose clause allows for an error to exist inside of the whose without breaking the entire statement.