Don't access value if property doesn't exist.

cbcd0ffb · Gus Grubba · ea55acec · cbcd0ffb
Commit cbcd0ffb authored Oct 26, 2018 by Gus Grubba
--- a/src/ui/preferences/GeneralSettings.qml
+++ b/src/ui/preferences/GeneralSettings.qml
@@ -504,7 +504,7 @@ QGCView {
                            Item { width: rtkGrid.firstColWidth; height: 1 }
                            QGCButton {
                                text:               qsTr("Save Current Base Position")
-                                enabled:            QGroundControl.gpsRtk.valid.value
+                                enabled:            QGroundControl.gpsRtk && QGroundControl.gpsRtk.valid.value
                                Layout.columnSpan:  2

                                onClicked: {