Normalize an optional boolean param. Accepts a real boolean or the strings
'true'/'false', case-insensitive. Anything else is an error rather than a
truthiness coercion — 'false' is truthy in JavaScript, and treating it as
true on a verify flag would be a silent, expensive surprise.
Normalize an optional boolean param. Accepts a real boolean or the strings 'true'/'false', case-insensitive. Anything else is an error rather than a truthiness coercion —
'false'is truthy in JavaScript, and treating it astrueon a verify flag would be a silent, expensive surprise.