Edit Image doesn't work on custom header/background screen and in Customizer

[ocean90]

Steps to reproduce:

• Go to themes.php?page=custom-header
• Click "Choose Image" to select an image from media library
• Select an image and click "Edit Image" link in attachment details

You will notice that nothing happens. Try to select another image now, broken too.

From the JS console:

Uncaught TypeError: Cannot call method 'single' of undefined media-views.js?ver=3.9-beta2-27714-src:4313
media.view.Attachment.media.View.extend.details media-views.js?ver=3.9-beta2-27714-src:4313
media.view.Attachment.media.View.extend.initialize media-views.js?ver=3.9-beta2-27714-src:4094
media.view.Attachment.Details.media.view.Attachment.extend.initialize media-views.js?ver=3.9-beta2-27714-src:5569
Backbone.View backbone.js?ver=1.1.2:1001
wp.Backbone.View.Backbone.View.extend.constructor wp-backbone.js?ver=3.9-beta2-27714-src:349
media.View.wp.Backbone.View.extend.constructor media-views.js?ver=3.9-beta2-27714-src:1398
child backbone.js?ver=1.1.2:1566
child backbone.js?ver=1.1.2:1566
media.view.AttachmentsBrowser.media.View.extend.createSingle media-views.js?ver=3.9-beta2-27714-src:5132
triggerEvents backbone.js?ver=1.1.2:208
Backbone.Events.trigger backbone.js?ver=1.1.2:148
_.extend._onModelEvent backbone.js?ver=1.1.2:946
triggerEvents backbone.js?ver=1.1.2:209
Backbone.Events.trigger backbone.js?ver=1.1.2:149
media.model.Selection.Attachments.extend.single media-models.js?ver=3.9-beta2-27714-src:1279
triggerEvents backbone.js?ver=1.1.2:208
Backbone.Events.trigger backbone.js?ver=1.1.2:148
_.extend.reset backbone.js?ver=1.1.2:770
media.view.Attachment.media.View.extend.toggleSelection media-views.js?ver=3.9-beta2-27714-src:4253
media.view.Attachment.media.View.extend.toggleSelectionHandler media-views.js?ver=3.9-beta2-27714-src:4190
n.event.dispatch jquery.js?ver=1.11.0:3
r.handle jquery.js?ver=1.11.0:3

[nacin]

Yeah, the link should be hidden for these workflows.

[ocean90]

Same for Customizer.

[gcorne]

This is an issue because the image edit state was not one of the states in the custom header frame. 27551-01.patch​ fixes this issue, which third-party plugins could also hit. We still may want to either add the ImageEdit state to this frame or remove the link for UX reasons, but the patch should keep things from exploding.

[nacin]

In 27787:

Avoid JS errors when edit image is not available, such as outside of post editing.

props gcorne.
fixes #27551.