fix unverified operation

src/AprsService.scala

@@ -93,13 +93,6 @@ class AprsService extends Service with LocationListener {
 	}
 
 	def startPoster() {
-		var passcode = prefs.getString("passcode", "")
-		if (passcode == "")
-			passcode = "-1"
-		val login = AprsPacket.formatLogin(prefs.getString("callsign", null).trim(),
-			prefs.getString("ssid", null), passcode)
-		val filterdist = prefs.getString("filterdist", "10").toInt
-
 		poster = AprsIsUploader.instanciateUploader(this, prefs)
 		poster.start()
 	}

src/backend/AprsIsUploader.scala

@@ -14,8 +14,12 @@ object AprsIsUploader {
 }
 
 abstract class AprsIsUploader(prefs : SharedPreferences) {
+	val passcode = prefs.getString("passcode", "") match {
+		case "" => "-1"
+		case s => s
+	}
 	val login = AprsPacket.formatLogin(prefs.getString("callsign", null).trim(),
-		prefs.getString("ssid", null), prefs.getString("passcode", null))
+		prefs.getString("ssid", null), passcode)
 
 	def start()