Error evaluating properties of qbs in Group condition when condition of product is false and qbs.install is defined in the Group

import qbs

Product {
    condition: false

    Group {
        condition: !qbs.targetOS.contains("__undefined__")

        // error occurs if this property's PRESENT at all, no matter the value
        // comment it out and the error goes away...
        qbs.install: undefined
    }
}

ERROR: /private/tmp/QBS-671/QBS-671.qbs:7 TypeError: Result of expression 'qbs.targetOS' [undefined] is not an object.