Fix potential crash in 'Save this waypoint between sessions'

diff --git a/TomTom.lua b/TomTom.lua
index 9542c48..74e0db7 100755
--- a/TomTom.lua
+++ b/TomTom.lua
@@ -569,7 +569,7 @@ end,
             local mapId = data[1]

             if mapId then
-                if UIDIsSavedTomTom.waypointprofile[mapId][key] then
+                if TomTom:UIDIsSaved(uid) then
                     TomTom.waypointprofile[mapId][key] = nil
                 else
                     TomTom.waypointprofile[mapId][key] = data