Wp-calypso: Unable to add menu items when Varia theme is active in Customizer (Atomic)

[samiff]

Steps to reproduce

1. On a WordPress.com AT site, activate Varia or one of the Varia child themes.
2. Attempt to add a menu item to an existing menu in the Customizer.

What I expected

• For a menu item to be added without error.

What happened instead

• A JS error is thrown:

Uncaught TypeError: Cannot read property 'open' of undefined
customize-nav-menus.min.js:2 
https://c0.wp.com/c/5.4.2/wp-admin/js/customize-nav-menus.min.js

• This doesn't seem to affect WordPress.com simple sites.
• WP Admin menu editing works as normal.
• Non-Varia themes and menu editing in Customizer as normal.

Browser / OS version

• Chrome Version 84.0.4147.89 (Official Build) (64-bit)

Context / Source

p1595975204029300-slack-wpcom-support

[samiff]

3181586-zen

[wprhunt]

3181628-zen

[annacmc]

Two accounts of this, both on Varia child themes (Hever & Balansala) #3181565-zen & #3181566-zen

[hacchism]

Another one with Hever: #22984068-hc

[adelineyaw]

22822319-hc (Rockfield theme)
Follow up: 3181846-zen

[sanjeev00733]

Another issue reported in #3182097-zen (Redhill theme)

[rachelwinspear]

Same issue came up in Quick Start. Brompton theme #3181169-zen

[nickpagz]

Another report with Morden #23003980-hc

[davipontesblog]

Another report with Redhill #22802372-hc

[aisajib]

Had an issue with Barnsbury here: #23005953-hc - user was trying to add a site logo (but they may have added/modified the menu section as well). Followup #3183283-zen

Edit: I've followed up with the user.

[JoshuaGoode]

Added tags, assigned to Dotcom manage.

Noting the following internal discussion threads

• Atomic: p1596026527494600-slack-atomic
• Themes: p1596024809179600-slack-themes

@jeffikus has reviewed but hasn't been able to identify the issue.

[scosgro]

Another report in 23010052-hc

[JoshuaGoode]

Updated users with tickets listed to let and had not already been informed that this has been resolved.

For chats listed, if you created a follow-up but didn't list the ticket -- or let the user know we would follow-up -- can you update them? Or, ping me and I can get to it.

cc: @davipontesblog @nickpagz @hacchism

[davipontesblog]

For chats listed, if you created a follow-up but didn't list the ticket -- or let the user know we would follow-up -- can you update them? Or, ping me and I can get to it.

Let the user know in #3186945-zen
thanks for the ping @JoshuaGoode !