Fix resend crash

app/src/main/java/chat/rocket/android/fragment/chatroom/RoomPresenter.java

@@ -114,7 +114,8 @@ public class RoomPresenter extends BasePresenter<RoomContract.View>
 
   @Override
   public void resendMessage(Message message) {
-    final Disposable subscription = messageInteractor.resend(message)
+    final Disposable subscription = getCurrentUser()
+        .flatMap(user -> messageInteractor.resend(message, user))
         .subscribeOn(AndroidSchedulers.from(BackgroundLooper.get()))
         .observeOn(AndroidSchedulers.mainThread())
         .subscribe();
@@ -204,11 +205,7 @@ public class RoomPresenter extends BasePresenter<RoomContract.View>
   private Single<Pair<Room, User>> getRoomUserPair() {
     return Single.zip(
         getSingleRoom(),
-        userRepository.getCurrent()
-            .filter(Optional::isPresent)
-            .map(Optional::get)
-            .firstElement()
-            .toSingle(),
+        getCurrentUser(),
         Pair::new
     );
   }
@@ -218,4 +215,12 @@ public class RoomPresenter extends BasePresenter<RoomContract.View>
         .firstElement()
         .toSingle();
   }
+
+  private Single<User> getCurrentUser() {
+    return userRepository.getCurrent()
+        .filter(Optional::isPresent)
+        .map(Optional::get)
+        .firstElement()
+        .toSingle();
+  }
 }

rocket-chat-core/src/main/java/chat/rocket/core/interactors/MessageInteractor.java

@@ -63,9 +63,10 @@ public class MessageInteractor {
     return messageRepository.save(message);
   }
 
-  public Single<Boolean> resend(Message message) {
+  public Single<Boolean> resend(Message message, User sender) {
     return messageRepository.save(
-        message.withSyncState(SyncState.NOT_SYNCED));
+        message.withSyncState(SyncState.NOT_SYNCED)
+            .withUser(sender));
   }
 
   public Single<Boolean> delete(Message message) {

rocket-chat-core/src/main/java/chat/rocket/core/models/Message.java

@@ -40,6 +40,8 @@ public abstract class Message {
 
   public abstract Message withSyncState(int syncState);
 
+  public abstract Message withUser(User user);
+
   public static Builder builder() {
     return new AutoValue_Message.Builder();
   }