[wp-trac] [WordPress Trac] #45341: WSOD when editing a page (Issue introduced between v5Beta3 and v5Beta4)

[WordPress Trac]

#45341: WSOD when editing a page (Issue introduced between v5Beta3 and v5Beta4)
--------------------------------------+------------------------------
 Reporter:  timhibberd                |       Owner:  (none)
     Type:  defect (bug)              |      Status:  new
 Priority:  normal                    |   Milestone:  Awaiting Review
Component:  Editor                    |     Version:  5.0
 Severity:  critical                  |  Resolution:
 Keywords:  needs-patch dev-feedback  |     Focuses:
--------------------------------------+------------------------------

Comment (by timhibberd):

 Still an issue in 5.0-RC1-43944.

 This looks like a race condition in the REACT / Webpack centric Javascript
 on the EditPage.

 I switched to 2019 theme and kept only one browser tab open to focus my
 testing and can now occasionally switch a viewed page into edit mode. But
 the page edit fails with Javacript errors 90% of the time. No issue with
 viewing existing pages. Just can't Add New pages or edit existing pages.

 Here is the latest Javascript errors:


 {{{
 09:20:32.679 SyntaxError: missing } after property list[Learn More]
 editor.js:19359:34 note: { opened at line 19354, column
 53editor.js:19354:53
 09:20:32.699 TypeError: Object(...) is not a function[Learn More] block-
 library.js:1740:67
 09:20:32.719 TypeError: Object(...)(...) is undefined[Learn More] edit-
 post.js:2102:16
 09:20:32.904 TypeError: wp.editPost is undefined[Learn More]
 post.php:1732:4
 }}}

 If I refresh the page sometimes it works. Another failure, different from
 the previous, simply by refreshing the edit page:


 {{{
 09:22:41.637 SyntaxError: unexpected token: identifier[Learn More]
 components.js:23536:33
 09:22:41.756 TypeError: external_this_wp_components_ is undefined[Learn
 More] editor.js:14135:1
 09:22:41.776 TypeError: external_this_wp_components_ is undefined[Learn
 More] block-library.js:1515:5
 09:22:41.790 TypeError: external_this_wp_components_ is undefined[Learn
 More] edit-post.js:1113:5
 09:22:41.795 TypeError: external_this_wp_components_ is undefined[Learn
 More] format-library.js:1162:34
 09:22:41.960 TypeError: wp.editPost is undefined[Learn More]
 post.php:1732:4
 }}}

 Here is another failure:


 {{{
 09:24:22.888 SyntaxError: '' string literal contains an unescaped line
 break components.js:24146:377
 09:24:23.011 TypeError: external_this_wp_components_ is undefined[Learn
 More] editor.js:14135:1
 09:24:23.034 TypeError: external_this_wp_components_ is undefined[Learn
 More] block-library.js:1515:5
 09:24:23.049 TypeError: external_this_wp_components_ is undefined[Learn
 More] edit-post.js:1113:5
 09:24:23.055 TypeError: external_this_wp_components_ is undefined[Learn
 More] format-library.js:1162:34
 09:24:23.218 TypeError: wp.editPost is undefined[Learn More]
 post.php:1732:4
 }}}

 The edit page refresh after this error worked with no fatal Javascript
 errors.

 The subsequent edit page refresh failed (notice it is the same error as
 previous but at a different line:

 {{{
 09:26:39.663 SyntaxError: "" string literal contains an unescaped line
 break components.js:23712:27
 09:26:39.781 TypeError: external_this_wp_components_ is undefined[Learn
 More] editor.js:14135:1
 09:26:39.803 TypeError: external_this_wp_components_ is undefined[Learn
 More] block-library.js:1515:5
 09:26:39.818 TypeError: external_this_wp_components_ is undefined[Learn
 More] edit-post.js:1113:5
 09:26:39.824 TypeError: external_this_wp_components_ is undefined[Learn
 More] format-library.js:1162:34
 09:26:39.998 TypeError: wp.editPost is undefined[Learn More]
 post.php:1732:4
 }}}

 This looks like a race condition problem to me. Race condition problems
 are nasty to track down and fix. Devastating in the field. You can't
 predict which sites it will affect or how many sites it will affect and
 there is no quick field fix to recommend to people. I would not recommend
 shipping WP5.0 until someone can work with me to try to isolate the root
 cause of these race condition errors.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/45341#comment:15>
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