Remove non-null assumption in electrum controller

The electrum controller assumes that the app connection daemon
is always initialized, which may not be the case and can trigger
crashes. Instead the model will just provide a null server if
the connection is unavailable which is correct and also prevents
crashes.

Author: dpad85

phoenix-shared/src/commonMain/kotlin/fr.acinq.phoenix/controllers/config/ElectrumConfigurationController.kt

@@ -7,6 +7,7 @@ import fr.acinq.phoenix.managers.AppConnectionsDaemon
 import fr.acinq.phoenix.controllers.AppController
 import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.launch
 import org.kodein.log.LoggerFactory
 
@@ -15,7 +16,7 @@ class AppElectrumConfigurationController(
     loggerFactory: LoggerFactory,
     private val configurationManager: AppConfigurationManager,
     private val electrumClient: ElectrumClient,
-    private val appConnectionsDaemon: AppConnectionsDaemon
+    private val appConnectionsDaemon: AppConnectionsDaemon?
 ) : AppController<ElectrumConfiguration.Model, ElectrumConfiguration.Intent>(
     loggerFactory = loggerFactory,
     firstModel = ElectrumConfiguration.Model()
@@ -24,14 +25,14 @@ class AppElectrumConfigurationController(
         loggerFactory = business.loggerFactory,
         configurationManager = business.appConfigurationManager,
         electrumClient = business.electrumClient,
-        appConnectionsDaemon = business.appConnectionsDaemon!!
+        appConnectionsDaemon = business.appConnectionsDaemon
     )
 
     init {
         launch {
             combine(
                 configurationManager.electrumConfig,
-                appConnectionsDaemon.lastElectrumServerAddress,
+                appConnectionsDaemon?.lastElectrumServerAddress ?: flow { null },
                 electrumClient.connectionStatus,
                 configurationManager.electrumMessages,
                 transform = { configState, currentServer, connectionStatus, message ->