Android Question WOBBLEMENU ERROR

I have downloaded a sample app under Wobblemenu but am getting this error any solution

wobblemenu_designercreateview (java line: 519)
java.lang.NumberFormatException: For input string: "null"
at java.lang.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1306)
at java.lang.Double.parseDouble(Double.java:547)
at anywheresoftware.b4a.BA.ObjectToNumber(BA.java:684)
at b4a.example.wobblemenu._designercreateview(wobblemenu.java:519)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:213)
at anywheresoftware.b4a.objects.CustomViewWrapper.AfterDesignerScript(CustomViewWrapper.java:67)
at anywheresoftware.b4a.keywords.LayoutBuilder.loadLayout(LayoutBuilder.java:162)
at anywheresoftware.b4a.objects.ActivityWrapper.LoadLayout(ActivityWrapper.java:209)
at b4a.example.main._activity_create(main.java:349)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:213)
at b4a.example.main.afterFirstLayout(main.java:105)
at b4a.example.main.access$000(main.java:17)
at b4a.example.main$WaitForLayout.run(main.java:83)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6121)
at java.lang.reflect.Method.invoke(Native Method)