Properly handling app resume cases when either the hostname or the MainPresenter is null

app/src/main/java/chat/rocket/android/activity/MainActivity.java

@@ -66,7 +66,14 @@ public class MainActivity extends AbstractAuthedActivity implements MainContract
   @Override
   protected void onResume() {
     super.onResume();
-    if (presenter != null) {
+    if (hostname == null || presenter == null) {
+      hostname = new RocketChatCache(getApplicationContext()).getSelectedServerHostname();
+      if (hostname == null) {
+        showAddServerScreen();
+      } else {
+        onHostnameUpdated();
+      }
+    } else {
       presenter.bindViewOnly(this);
       presenter.loadSignedInServers(hostname);
     }

app/src/main/java/chat/rocket/android/api/MethodCallHelper.java

@@ -52,7 +52,7 @@ public class MethodCallHelper {
    */
   public MethodCallHelper(Context context, String hostname) {
     this.context = context.getApplicationContext();
-    this.realmHelper = RealmStore.get(hostname);
+    this.realmHelper = RealmStore.getOrCreate(hostname);
     ddpClientRef = null;
   }