improvements in docs and null pointer fix

src/main/kotlin/eu/fosil/okupamicoche/Main.kt

@@ -1,6 +1,7 @@
 package eu.fosil.okupamicoche
 
 import eu.fosil.okupamicoche.config.ConfigReader
+import eu.fosil.okupamicoche.matrix.MatrixApiClient
 import eu.fosil.okupamicoche.matrix.createAppService
 import eu.fosil.okupamicoche.matrix.event.TravelEventContentSerializerMappings
 import eu.fosil.okupamicoche.matrix.matrixApiClient
@@ -24,10 +25,10 @@ suspend fun main() {
 
     requireNotNull(config)
     requireNotNull(matrixApiClient)
+    MatrixApiClient.init()
 
     coroutineScope {
         launch {
-
             val roomMainAlias = "#${config.mainRoom}:${config.homeserver.host}"
             val roomAliasRes = matrixApiClient.rooms.getRoomAlias(RoomAliasId(roomMainAlias)).getOrNull()
             if (roomAliasRes == null) {
@@ -38,10 +39,14 @@ suspend fun main() {
                 )
             } else {
                 val mainRoomId = roomAliasRes.roomId
-                val alreadyJoinedToMainRoom = (matrixApiClient.rooms.getJoinedRooms().getOrNull()?.filter { roomId ->
+                val joinedToMainRoom = (matrixApiClient.rooms.getJoinedRooms().getOrNull()?.filter { roomId ->
                     roomId == mainRoomId
                 }?.firstOrNull()) !== null
-                logger.info("alreadyJoinedToMainRoom=$alreadyJoinedToMainRoom")
+                logger.info("alreadyJoinedToMainRoom=$joinedToMainRoom")
+
+                if (!joinedToMainRoom) {
+                    matrixApiClient.rooms.joinRoom(mainRoomId)
+                }
 
                 val roomStateRes = matrixApiClient.rooms.getState(mainRoomId).getOrNull()
                 roomStateRes?.collect { stateEvent ->

src/main/kotlin/eu/fosil/okupamicoche/matrix/matrixApiClient.kt

@@ -22,7 +22,7 @@ val matrixApiClient = if (config == null) null else MatrixClientServerApiClient(
 object MatrixApiClient {
     var appServiceUserId: UserId? = null
 
-    init {
+    fun init() {
         requireNotNull(matrixApiClient)
 
         val ioScope = CoroutineScope(Dispatchers.IO)

src/main/kotlin/eu/fosil/okupamicoche/usecase/travel/createTravel.kt

@@ -53,6 +53,7 @@ suspend fun createTravel(
 private suspend fun createRoom(travelOptions: TravelOptions, driver: UserId): RoomId {
     requireNotNull(matrixApiClient)
     requireNotNull(config)
+    val appServiceUserId = requireNotNull(MatrixApiClient.appServiceUserId)
 
     val newRoomAliasAndName = getRoomAliasAndName(travelOptions)
     val initialState = Event.InitialStateEvent(
@@ -62,7 +63,7 @@ private suspend fun createRoom(travelOptions: TravelOptions, driver: UserId): Ro
     val powerLevels = PowerLevelsEventContent(
         events = mapOf(Pair(TRAVEL_CREATED_STATE_EVENT_ID, 100)),
         users = mapOf(
-            Pair(MatrixApiClient.appServiceUserId!!, 100),
+            Pair(appServiceUserId, 100),
             Pair(driver, 50)
         )
     )