remove duplicate request when timeline is empty (#1491)

app/src/main/java/com/keylesspalace/tusky/fragment/TimelineFragment.java

@@ -68,7 +68,6 @@ import com.keylesspalace.tusky.view.EndlessOnScrollListener;
 import com.keylesspalace.tusky.viewdata.StatusViewData;
 
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
@@ -286,12 +285,12 @@ public class TimelineFragment extends SFragment implements
     }
 
     private void updateCurrent() {
-        String topId;
         if (this.statuses.isEmpty()) {
-            topId = null;
-        } else {
-            topId = CollectionsKt.first(this.statuses, Either::isRight).asRight().getId();
+            return;
         }
+
+        String topId = CollectionsKt.first(this.statuses, Either::isRight).asRight().getId();
+
         this.timelineRepo.getStatuses(topId, null, null, LOAD_AT_ONCE,
                 TimelineRequestMode.NETWORK)
                 .observeOn(AndroidSchedulers.mainThread())
@@ -303,7 +302,7 @@ public class TimelineFragment extends SFragment implements
                             if (!statuses.isEmpty()) {
                                 filterStatuses(statuses);
 
-                                if (!this.statuses.isEmpty() && topId != null) {
+                                if (!this.statuses.isEmpty()) {
                                     // clear old cached statuses
                                     Iterator<Either<Placeholder, Status>> iterator = this.statuses.iterator();
                                     while (iterator.hasNext()) {