[balsa/gtk4: 80/312] Minor cleanup

[Peter Bloomfield <peterb src gnome org>]

commit a8f32ad7be772dd6cd2c15a0e839a74129c2cd2c
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Sun Jun 28 17:11:54 2020 -0400

    Minor cleanup
    
    libbalsa-vfs: Add guards
    balsa-mblist.c: Correct description

 libbalsa/libbalsa-vfs.c | 6 ++++++
 src/balsa-mblist.c      | 7 +++----
 2 files changed, 9 insertions(+), 4 deletions(-)
---
diff --git a/libbalsa/libbalsa-vfs.c b/libbalsa/libbalsa-vfs.c
index eae652d20..090090fed 100644
--- a/libbalsa/libbalsa-vfs.c
+++ b/libbalsa/libbalsa-vfs.c
@@ -534,6 +534,7 @@ libbalsa_vfs_launch_app(LibbalsaVfs * file, GAppInfo *app, GError **err)
     gboolean result;
 
     g_return_val_if_fail(LIBBALSA_IS_VFS(file), FALSE);
+    g_return_val_if_fail(app == NULL || G_IS_APP_INFO(app), FALSE);
 
     if (app == NULL) {
         g_set_error(err, LIBBALSA_VFS_ERROR_QUARK, -1,
@@ -559,6 +560,7 @@ libbalsa_vfs_launch_app_for_body(LibBalsaMessageBody *mime_body,
     gboolean result;
 
     g_return_val_if_fail(mime_body != NULL, FALSE);
+    g_return_val_if_fail(app == NULL || G_IS_APP_INFO(app), FALSE);
 
     if (!libbalsa_message_body_save_temporary(mime_body, err))
         return FALSE;
@@ -662,6 +664,10 @@ libbalsa_vfs_fill_menu_by_content_type(GMenu       *menu,
     GAppInfo *def_app;
     GList *app_list;
 
+    g_return_if_fail(G_IS_MENU(menu));
+    g_return_if_fail(G_IS_ACTION_MAP(action_map));
+    g_return_if_fail(G_IS_OBJECT(object));
+
     def_app = g_app_info_get_default_for_type(content_type, FALSE);
     if (def_app != NULL)
         gio_add_vfs_menu_item(menu, def_app, action_map, action_namespace, callback, object);
diff --git a/src/balsa-mblist.c b/src/balsa-mblist.c
index 3f90dccae..7035abede 100644
--- a/src/balsa-mblist.c
+++ b/src/balsa-mblist.c
@@ -2414,16 +2414,15 @@ bmbl_choose_mailbox(GtkWidget *widget)
 
 /*
  * balsa_mblist_mru_get_url,
- * balsa_mblist_mru_get_mailbox_from_url:
+ * balsa_mblist_mru_get_mailbox:
  *
  * Helpers for "_change_state" actions of mru_menus
  *
- * Get the url from the GVariant parameter. If it is "-",
+ * Get the url as GObject data from the object parameter. If it is NULL,
  * the user selected "Other...", so we must pop up the mailbox list dialog
  * and let the user choose the mailbox. That dialog can be canceled,
  * returning a NULL mailbox, so we must be careful; the caller must be
- * prepared for the return of a NULL url or mailbox,
- * respectively.
+ * prepared for the return of a NULL url or mailbox, respectively.
  */
 
 const gchar *