[wp-trac] [WordPress Trac] #52933: Error in browser console when newly published post is previewed a second time

[WordPress Trac]

#52933: Error in browser console when newly published post is previewed a second
time
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 Reporter:  garethhadfield  |       Owner:  (none)
     Type:  defect (bug)    |      Status:  new
 Priority:  normal          |   Milestone:  5.8
Component:  Editor          |     Version:
 Severity:  normal          |  Resolution:
 Keywords:                  |     Focuses:  javascript, rest-api
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Comment (by Rahmohn):

 I've tested this and can reproduce the issue too.

 The issue happens if there is already an autosave and the user clicks in
 "Preview in new tab" because this button
 [https://github.com/WordPress/gutenberg/blob/3da717b8d0ac7d7821fc6d0475695ccf3ae2829f/packages/editor/src/components
 /post-preview-button/index.js#L174 always tries to autosave the post]. So
 another way to reproduce this issue is by clicking on "Preview in new
 tab", reload the page and try to preview again.

 Other than that, Autosaves controller [https://github.com/WordPress
 /wordpress-develop/blob/5e8b165a54be9f72d3b323a81d5ba1e262b6f194/src/wp-
 includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php#L376
 deletes the autosave when the post data is the same]. So the next time the
 user tries to preview the issue doesn't happen.

 It's not clear to me the best approach to fix it. We can prevent the
 "Preview in new tab" button to send the request when the content hasn't
 changed. The behavior would be like the "Update" button. The second
 approach is changing the Autosave controller to return the previous
 autosave if the content is the same instead of a Bad Request (HTTP 400).

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Ticket URL: <https://core.trac.wordpress.org/ticket/52933#comment:4>
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