PWA error: null is not an object (evaluating 'e.ownerNode')

[ghost]

What's the issue?

In a multi shadow dow when swiping fast in an iOS device, the document doesn't initialize correctly causing the fix-layer to have a list of stylesheets with null values.
I believe there should be a check here:
https://github.com/ampproject/amphtml/blob/master/src/service/fixed-layer.js#L110

How do we reproduce the issue?

You can go to: https://www.starwarsnewsnet.com/2018/07/san-diego-comic-con-2018-preview-of-star-wars-related-content-and-our-sdcc-exclusive-giveaways.html
and swipe fast or use the next-article button

What browsers are affected?

Safari (any iphone)
And also emulating a mobile device in safari desktop.

Which AMP version is affected?

last one

[ghost]

I think this issue appeared after this commit: #15204

[aghassemi]

@juanchaur1 Thanks for the report. Sorry about the regression.

/to @jridgewell

Setting to P1 for now since breakage is limited to certain user interactions on PWA+AMP. If anyone believes this should be P0, please let us know.

[jpettitt]

/to @choumx (@jridgewell is OOO)

[erwinmombay]

This issue doesn't have a category which makes it harder for us to keep track of it. @jridgewell Please add an appropriate category.

[erwinmombay]

This is a high priority issue but it hasn't been updated in awhile. @jridgewell Do you have any updates?

[dreamofabear]

I can't find any traces in our "origin" error reports with "ownerNode" and it's strange that styleSheets would return a null entry. Also don't think this is caused by #15204.

Should be easy enough to add a null check to the loop though.

[ampprojectbot]

This is a high priority issue but it hasn't been updated in awhile. @jridgewell Do you have any updates?

[ampprojectbot]

This is a high priority issue but it hasn't been updated in awhile. @jridgewell Do you have any updates?

[ampprojectbot]

This is a high priority issue but it hasn't been updated in awhile. @jridgewell Do you have any updates?

[ampprojectbot]

This is a high priority issue but it hasn't been updated in awhile. @jridgewell Do you have any updates?

[dreamofabear]

@alabiaga Let's add that null-check as described in #17024 (comment).