Media: Replace button enabled when no media item selected

[timmydcrawford]

Initially discovered while working on the new Media Widgets for the customizer:
​https://github.com/xwp/wp-core-media-widgets/issues/102

Steps to Recreate:

• Open up a post in the editor
• Insert an image via the "Add Media" button
• Once the image is displayed in the editor, click the pencil icon to open the image editor modal
• Click the "Replace" button below the image
• Note the current image is selected in the replace view, and the "Replace" button is enabled
• Un-select the current image so no image is selected, note the "Replace" button is still enabled
• Click the "Replace" button, and an error will be thrown ( see screenshot )

Some logic could be added to prevent the exception, but ideally it seems like the "Replace" button should be disabled when there is no active selection.

[subrataemfluence]

Screen cast of step by step operation

[subrataemfluence]

Please disregard added screen cast. I missed the "trunk". Sorry for this.

[psiico]

patch

[adamsilverstein]

@psiico

Thanks for your work and patch here, and for providing the screencast.

We don't need to track selection in the click callback because the toolbar component already supports a section: required attribute that produces the desired behavior.

40589.2.diff​ is an alternate approach that uses that feature.

Can you please test? Thanks.

[timmydcrawford]

40589.2.diff​ is testing out well for me - the button is disabled now until an item is selected.

[adamsilverstein]

In 40902:

Media: Disable the edit image->replace button when no item selected.

On the edit media screen, ensure that the 'replace' button is disabled until a media item is selected. Fix an issue where clicking the button with no item selected threw a JavaScript error and failed to work.

Props timmydcrawford, subrataemfluence, psiico.
Fixes #40589.

[wonderboymusic]

#36453 was marked as a duplicate.