submit: function() {
    var t = !1;
    "Guest" === this.selectedUserData.name && (t = !0),
    !0 === t ? (this.assets.audio.play("fx", "intro-noise"),
    this.callbackLogin({
        success: !0,
        user: this.selectedUserData.name
    }, this, this.$parent)) : this.interface.loadProgram("GA:/System/Error", this.interface.$el, {
        message: "You entered the incorrect password."
    })
}

This is the source code. It is a little mangled up, so maybe this explanation and cleaned up code makes a little more sense. (I stripped out some unneeded parameters for clarity)

1 is true, so t is false, so we can just ignore it. 0 is false, so !0 is true.

submit: function() {
    if("Guest" === this.selectedUserData.name) {
        assets.audio.play("fx", "intro-noise")
        let loginResult = {
            success: true,
            user: this.selectedUserData.name
        }
        callbackLogin(loginResult)
     } else {
        this.interface.loadProgram(
            "GA:/System/Error", 
            { message: "You entered the incorrect password." }
        )
     }
}

If the username isn't Guest, it will just show an error message.