fix: Proces threading fix

app/src/main/java/eu/ztsh/garmin/Garmin.kt

@@ -23,7 +23,7 @@ class Garmin(
 ) {
 
     private lateinit var connection: ConnectThread
-    private lateinit var processing: ProcessingThread
+    private val observer = ProcessingThreadObserver()
     private val cache = DataCache()
 
     fun start() {
@@ -36,15 +36,11 @@ class Garmin(
     }
 
     fun process(maneuver: Maneuver) {
-        processing = ManeuverProcessingThread(maneuver)
-        processing.start()
-        processing.join()
+        ManeuverProcessingThread(maneuver).start()
     }
 
     fun process(location: LocationMatcherResult) {
-        processing = LocationProcessingThread(location)
-        processing.start()
-        processing.join()
+        LocationProcessingThread(location).start()
     }
 
     fun process(navigationSessionState: NavigationSessionState) {
@@ -83,6 +79,15 @@ class Garmin(
                 connection.enqueue(GarminMapper.setDirection(incoming))
             }
             cache.update(incoming)
+            observer.join(this)
+        }
+
+    }
+
+    private inner class ProcessingThreadObserver {
+
+        fun join(thread: ProcessingThread) {
+            thread.join()
         }
 
     }
@@ -165,6 +170,8 @@ class Garmin(
 
     companion object {
 
+        lateinit var instance: Garmin
+
         fun prepareData(input: IntArray): IntArray {
             val n = input.size
             var crc = (0xeb + n + n).toUInt()