A 0 value returns false for this statement, so as suggested by yourself, changing this to be a 'does have value at all?' check would solve this. Included is JavaScript used to test this;

wizSpinner.show({bgColor: "#000", opacity: 0.5, customSpinner: true, spinnerDuration: 0.5, spinnerLoops: 0})

wizSpinner.hide()

wizSpinner.show({bgColor: "#000", opacity: 0.5, customSpinner: true, spinnerDuration: 0.5, spinnerLoops: 2})

wizSpinner.hide()

wizSpinner.show({bgColor: "#000", opacity: 0.5, customSpinner: true, spinnerDuration: 0.5, spinnerLoops: 0})