fix compile error and segfault after cancel of dnd tag creation

src/Widgets/FeedList.vala

@@ -24,6 +24,7 @@ public class FeedReader.feedList : Gtk.Stack {
 	private ServiceInfo m_branding;
 	private uint m_expand_collapse_time = 150;
 	private bool m_update = false;
+	private bool m_busy = false;
 	private bool m_TagsDisplayed = false;
 	public signal void newFeedSelected(string feedID);
 	public signal void newTagSelected(string tagID);
@@ -191,6 +192,14 @@ public class FeedReader.feedList : Gtk.Stack {
 	public void newFeedlist(bool defaultSettings, bool masterCat = false)
 	{
 		logger.print(LogMessage.DEBUG, "FeedList: new FeedList");
+
+		if(m_busy)
+		{
+			logger.print(LogMessage.DEBUG, "FeedList: busy");
+			return;
+		}
+
+		m_busy = true;
 		m_branding.refresh();
 		var FeedChildList = m_list.get_children();
 
@@ -215,6 +224,7 @@ public class FeedReader.feedList : Gtk.Stack {
 		createFeedlist(defaultSettings, masterCat);
 		settings_state.set_boolean("no-animations", false);
 		m_update = false;
+		m_busy = false;
 	}
 
 
@@ -964,7 +974,18 @@ public class FeedReader.feedList : Gtk.Stack {
 	public void removeEmptyTagRow()
 	{
 		logger.print(LogMessage.DEBUG, "removeEmptyTagRow");
-		removeRow(m_emptyTagRow, 250);
+
+		if(m_busy)
+		{
+			logger.print(LogMessage.DEBUG, "FeedList: busy");
+			return;
+		}
+
+		if(m_emptyTagRow != null)
+		{
+			removeRow(m_emptyTagRow, 250);
+			m_emptyTagRow = null;
+		}
 	}
 
 	public void deselectRow()

src/Widgets/MainWindow.vala

@@ -590,7 +590,7 @@ public class FeedReader.readerUI : Gtk.ApplicationWindow
 				m_ErrorMessage.set_label(_("No valid CA certificate available!"));
 				m_ignore_tls_errors.set_visible(true);
 				break;
-			case LoginResponse.CA_ERROR:
+			case LoginResponse.PLUGIN_NEEDED:
 				m_ErrorMessage.set_label(_("Please install the \"api_feedreader\"-plugin on your tt-rss instance!"));
 				m_ignore_tls_errors.set_visible(true);
 				break;

src/Widgets/TagRow.vala

@@ -255,12 +255,11 @@ public class FeedReader.TagRow : Gtk.ListBoxRow {
 			this.unset_state_flags(Gtk.StateFlags.PRELIGHT);
 			if(m_tagID == TagID.NEW && context != null)
 			{
-				removeRow();
 				if(Utils.haveTags())
 				{
 					var window = ((FeedApp)GLib.Application.get_default()).getWindow();
 					var feedlist = window.getContent().getFeedList();
-					feedlist.newFeedlist(false, false);
+					//feedlist.newFeedlist(false, false);
 				}
 				Gtk.drag_finish(context, true, false, time);
 			}