add some null-pointer checks in for diaalog code

src/form.c

@@ -390,7 +390,12 @@ static void
 parse_cmd_output (gchar *data)
 {
   guint i = 0;
-  gchar **lines = g_strsplit (data, "\n", 0);
+  gchar **lines;
+
+  if (!data)
+    return;
+
+  lines = g_strsplit (data, "\n", 0);
 
   disable_changed = TRUE;
   while (lines[i] && lines[i][0])

src/list.c

@@ -1495,7 +1495,7 @@ print_col (GtkTreeModel *model, GtkTreeIter *iter, gint num)
         gtk_tree_model_get (model, iter, num, &val, -1);
         if (options.common_data.quoted_output)
           {
-            gchar *buf = g_shell_quote (val);
+            gchar *buf = g_shell_quote (val ? val : "");
             g_printf ("%s", buf);
             g_free (buf);
           }