StringType Error in Rule

In the rule below I am getting the error message: Expected org.openhab.core.library.types.StringType but was Java.lang.string in this line: if (user == null) user = “user unknown” .
I tried various ways to try to fix it but couldn’t get anything to work. Thanks for any help.

rule "Alarm Panel Armed (Any)"
    Item AlarmArea1ArmMode changed from Disarmed to Armed
    say("Warning! House Armed Notification")

    // Perform deferred notifications, as the User.state may not have been processed yet.
    createTimer(now.plusSeconds(1)) [
        logDebug("house-alarm", "Alarm-Panel-Armed-Any Deferred notification")
        var user = AlarmArea1LastUser.state as StringType

        if (user == null) user = "user unknown"
        pushNotification("House-Armed", "House Armed Notification (" + user + ")")


var user = AlarmArea1LastUser.state.toString()

That eliminated the error. Thanks for the fast response.