Show warning if the menu name already exists

[ocean90]

At the moment you get a warning:

Notice: Trying to get property of non-object in H:\xampplite\htdocs\wp\wp-admin\nav-menus.php  on line 208

and a wrong message, because it hasn't been created.

The  menu has been successfully created.

[ocean90]

There is somethink similar:

Create a menu with name 1 and a menu with name 2, after that change the name of 2 to 1. The name of menu 2 should be now 1.

If you change the name, you should also get this warning:

Notice: Undefined index: menu-item-db-id in H:\xampplite\htdocs\wp\wp-admin\nav-menus.php  on line 232

[ocean90]

Not as Cc...

[ocean90]

Notice: Undefined index: menu-item-db-id in H:\xampplite\htdocs\wp\wp-admin\nav-menus.php  on line 232

You get this message, if the menu doesn't have any items.

[nacin]

(In [14283]) More nav menu fixes. props filosofo. see #13148. fixes #13155, fixes #13157, fixes #13138, see #13134.

[ocean90]

see #comment:1 and #comment:3

[nacin]

(In [14285]) Fix handling of nav menu search, also menu naming conflicts. props filosofo, fixes #13138