projectorganizer: Make sure project is open before trying to expand t…

…he tree

Since expand_on_idle() is called as an idle function, it can happen it's
executed after project is closed in which case it should just return
without accessing variables with invalid values.

Should fix crash reported in #549.

projectorganizer/src/prjorg-sidebar.c

@@ -1214,6 +1214,9 @@ static gboolean expand_on_idle(gpointer ptr)
 {
 	GeanyDocument *doc = document_get_current();
 
+	if (!geany_data->app->project || !prj_org)
+		return FALSE;
+
 	if (ptr)
 	{
 		GPtrArray *expanded_paths = ptr;
@@ -1225,7 +1228,7 @@ static gboolean expand_on_idle(gpointer ptr)
 		g_ptr_array_free(expanded_paths, TRUE);
 	}
 
-	if (!s_follow_editor || !doc || !doc->file_name || !geany_data->app->project || !prj_org)
+	if (!s_follow_editor || !doc || !doc->file_name)
 		return FALSE;
 
 	expand_path(doc->file_name, TRUE);