Couldn’t find an adobe doc for

exceptionKeyExists()

it appears to have worked since CF2016: https://cfdocs.org/exceptionkeyexists here’s how I assume it work (and it does):

try {
    x = 5/0;
} catch (any err) {
    if (exceptionKeyExists(err, "message")) {
        writeOutput("Error has message key");
    }
}