More crash fixes

mastodon/src/main/java/org/joinmastodon/android/fragments/HomeTimelineFragment.java

@@ -48,6 +48,8 @@ public class HomeTimelineFragment extends StatusListFragment{
 				.getHomeTimeline(offset>0 ? getMaxID() : null, count, refreshing, new SimpleCallback<>(this){
 					@Override
 					public void onSuccess(List<Status> result){
+						if(getActivity()==null)
+							return;
 						onDataLoaded(result, !result.isEmpty());
 					}
 				});

mastodon/src/main/java/org/joinmastodon/android/fragments/NotificationsListFragment.java

@@ -103,6 +103,8 @@ public class NotificationsListFragment extends BaseStatusListFragment<Notificati
 				.getNotifications(offset>0 ? getMaxID() : null, count, onlyMentions, refreshing, new SimpleCallback<>(this){
 					@Override
 					public void onSuccess(List<Notification> result){
+						if(getActivity()==null)
+							return;
 						if(refreshing)
 							relationships.clear();
 						onDataLoaded(result.stream().filter(n->n.type!=null).collect(Collectors.toList()), !result.isEmpty());

mastodon/src/main/java/org/joinmastodon/android/fragments/discover/DiscoverAccountsFragment.java

@@ -121,6 +121,15 @@ public class DiscoverAccountsFragment extends BaseRecyclerFragment<DiscoverAccou
 		}).exec(accountID);
 	}
 
+	@Override
+	public void onDestroyView(){
+		super.onDestroyView();
+		if(relationshipsRequest!=null){
+			relationshipsRequest.cancel();
+			relationshipsRequest=null;
+		}
+	}
+
 	@Override
 	public void scrollToTop(){
 		smoothScrollRecyclerViewToTop(list);