Work around db.read_tag() returning null

This shouldn't happen, but it does sometimes. For now, at least make us not crash.

Author: brendanlong

src/Widgets/RemovePopover.vala

@@ -82,7 +82,9 @@ private void removeTag()
 	var notification = MainWindow.get_default().showNotification(text);
 
 	ulong eventID = notification.dismissed.connect(() => {
-			FeedReaderBackend.get_default().deleteTag(DataBase.readOnly().read_tag(m_id));
+			var tag = DataBase.readOnly().read_tag(m_id);
+			if(tag != null)
+				FeedReaderBackend.get_default().deleteTag(tag);
 		});
 	notification.action.connect(() => {
 			notification.disconnect(eventID);

src/Widgets/TagPopover.vala

@@ -35,7 +35,12 @@ public TagPopover(Gtk.Widget widget)
 		Gee.List<string> tagIDs = selectedArticle.getTagIDs();
 		foreach(string tagID in tagIDs)
 		{
-			m_tags.add(db.read_tag(tagID));
+			var tag = db.read_tag(tagID);
+			// FIXME: Sometimes articles claim to have tags that don't exist
+			// in the DB. This works around that but we should fix the
+			// underlying problem at some point
+			if (tag != null)
+				m_tags.add(tag);
 		}
 	}