🚨 Error: Cannot read property 'setAttribute' of null

[ampprojectbot]

Details

Error report: link
First seen: Oct 17, 2019
Frequency: ~ 8114/day

Stacktrace

Error: Cannot read property 'setAttribute' of null
    at setAttribute (https://raw.githubusercontent.com/ampproject/amphtml/2004012158290/src/service/extensions-impl.js:258)
    at reloadExtension (https://raw.githubusercontent.com/ampproject/amphtml/2004012158290/src/runtime.js:472)
    at maybeLoadCorrectVersion (https://raw.githubusercontent.com/ampproject/amphtml/2004012158290/src/runtime.js:241)
    at (https://raw.githubusercontent.com/ampproject/amphtml/2004012158290/src/service/timer-impl.js:83)

@choumx modified src/service/extensions-impl.js:258-259 in #24730 (Oct 1, 2019)
@jridgewell modified src/runtime.js:472-472 in #24402 (Sep 6, 2019)
@cramforce modified src/service/timer-impl.js:81-88 in #7363 (Feb 7, 2017)

Potential assignees: @choumx, @jridgewell

[rcebulko]

It looks like this error started surfacing a short while after #24730 was merged. There is a devAssert() to verify that the el exists with the warning 'Cannot find script for extension: %s', extensionId. It looks like this happens when an extension <script> tag is missing.

@choumx Am I correct that this should only be possible on non-valid AMPs? It seems maybe this should raise a user().error() explicitly and bail out before trying to set attributes on the element. If that's the case, I'm happy to throw together a PR with this fix

[rcebulko]

I'll add that the volume of this error was pretty low until recently, but it seems most of the recent referrers are AliExpress, indicating they probably have this (mis)?configuration on one of their pages, which brought this error to the front page.

[dreamofabear]

Somewhat confusing. It appears that this would happen if an extension is added to preregisteredExtensions but the extension script is missing. Need to look at a repro page to pinpoint the issue.

[dreamofabear]

#29042 should fix this too.