fix(StatusDisplayItem): check if account is null before adding quote

This should fix crashes in the ScheduledStatusListFragment,
as ScheduledStatus do not contain an account.

mastodon/src/main/java/org/joinmastodon/android/ui/displayitems/StatusDisplayItem.java

@@ -341,7 +341,7 @@ public static ArrayList<StatusDisplayItem> buildItems(BaseStatusListFragment<?>
 				if(!statusForContent.mediaAttachments.isEmpty() && statusForContent.poll==null) // add spacing if immediately preceded by attachment
 					contentItems.add(new DummyStatusDisplayItem(parentID, fragment));
 				contentItems.addAll(buildItems(fragment, statusForContent.quote, accountID, parentObject, knownAccounts, filterContext, FLAG_NO_FOOTER|FLAG_INSET|FLAG_NO_EMOJI_REACTIONS|FLAG_IS_FOR_QUOTE));
-			} else if((flags & FLAG_INSET)==0 && statusForContent.mediaAttachments.isEmpty()){
+			} else if((flags & FLAG_INSET)==0 && statusForContent.mediaAttachments.isEmpty() && statusForContent.account!=null){
 				tryAddNonOfficialQuote(statusForContent, fragment, accountID, filterContext);
 			}
 			if(contentItems!=items && statusForContent.spoilerRevealed){
@@ -431,6 +431,7 @@ private static void tryAddNonOfficialQuote(Status status, BaseStatusListFragment
 			return;
 		String quoteURL=matcher.group();
 
+		// account may be null for scheduled posts
 		if (!UiUtils.looksLikeFediverseUrl(quoteURL))
 			return;