[epiphany] prefs-general-page: Prevent adding the same language multiple times

[Michael Catanzaro <mcatanzaro src gnome org>]

commit d8242df0ab3207cde821c0ebe04e5ac3e4d9e7d8
Author: Yetizone <andreii lisita gmail com>
Date:   Mon Sep 14 22:15:45 2020 +0300

    prefs-general-page: Prevent adding the same language multiple times
    
    Fixes https://gitlab.gnome.org/GNOME/epiphany/-/issues/1335

 src/preferences/prefs-general-page.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/preferences/prefs-general-page.c b/src/preferences/prefs-general-page.c
index 7c42eb129..9d6460b14 100644
--- a/src/preferences/prefs-general-page.c
+++ b/src/preferences/prefs-general-page.c
@@ -474,7 +474,7 @@ language_editor_add (PrefsGeneralPage *general_page,
     GtkListBoxRow *widget;
     char *row_code;
 
-    widget = gtk_list_box_get_row_at_index (GTK_LIST_BOX (general_page->lang_listbox), index++);
+    widget = gtk_list_box_get_row_at_index (GTK_LIST_BOX (general_page->lang_listbox), index);
 
     row_code = g_object_get_data (G_OBJECT (widget), "code");
     if (row_code && strcmp (row_code, code) == 0)