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: if (exists true whose ( if true then ( exists name of operating system ) else false )) then (name of operating system as string ) else (“The relevance does not work on this version/platform of BigFix”)
A: Win2016
q: if (exists true whose ( if true then ( exists releaseid of operating system ) else false )) then (releaseid of operating system as string ) else (“The relevance does not work on this version/platform of BigFix”)
A: 1607