VPN-7596: early return when needed (#11259)

* VPN-7596 early return when needed

* add logging

Author: mcleinman

src/controller.cpp

@@ -504,6 +504,7 @@ void Controller::activateInternal(
   QList<InterfaceConfig> serverConfigs =
       setupConfigs(dnsPort, serverSelectionPolicy);
   if (serverConfigs.isEmpty()) {
+    logger.info() << "Config setup error";
     // Error in setupConfigs, so do not continue
     return;
   }
@@ -900,7 +901,17 @@ void Controller::maybeSendUpdatedConfig(const ServerData& serverData) {
     m_serverData = serverData;
     QList<InterfaceConfig> serverConfigs =
         setupConfigs(DoNotForceDNSPort, RandomizeServerSelection);
+    if (serverConfigs.isEmpty()) {
+      // Error in setupConfigs, so do not continue
+      // This most commonly happens when signing out -
+      // Controller::serverDataChanged is called because all settings emit a
+      // changed signal while updating the settings during sign out. However
+      // when signing out, there is no new server data to send.
+      logger.info() << "Error setting up configs";
+      return;
+    }
     Q_ASSERT(serverConfigs.size() == 1 || serverConfigs.size() == 2);
+
     InterfaceConfig exitConfig = serverConfigs.takeLast();
     InterfaceConfig entryConfig;
     if (!serverConfigs.isEmpty()) {