Failed to process trigger "ad-request-start"

[adelinamart]

@lannka please look at this error asap. It started with the current production

Error: AmpAnalytics Failed to process trigger "ad-request-start": null is not an object (evaluating 'a.na.addTrigger')
at addTrigger (https://raw.githubusercontent.com/ampproject/amphtml/1809142227020/extensions/amp-analytics/0.1/amp-analytics.js:388)
at addTriggerNoInline_ (https://raw.githubusercontent.com/ampproject/amphtml/1809142227020/extensions/amp-analytics/0.1/amp-analytics.js:314)

Version
011809142227020
https://pantheon.corp.google.com/errors/CPiQyKiMp7qR1gE?service=default-cdn-1p&time=P1D&project=amp-error-reporting

Error: AmpAnalytics Failed to process trigger "ad-render-start": a.na is null
at analyticsGroup_ (https://raw.githubusercontent.com/ampproject/amphtml/1809142227020/extensions/amp-analytics/0.1/amp-analytics.js:388)
at addTriggerNoInline_ (https://raw.githubusercontent.com/ampproject/amphtml/1809142227020/extensions/amp-analytics/0.1/amp-analytics.js:314)

https://pantheon.corp.google.com/errors/CLehgcix6Y60GA?service&time=P1D&filter=text:Failed%20to%20process%20trigger%20%22ad-request-start%22&project=amp-error-reporting

[lannka]

@calebcordry can you please take a look? It is from the AMP story analytics triggers.

[calebcordry]

Looking now.

[calebcordry]

Upon further investigation it seems like this error is coming from

amphtml/ads/google/a4a/utils.js

Lines 542 to 546 in ec06c78

	'triggers': {
	'adRequestStart': csiTrigger('ad-request-start', {
	// afs => ad fetch start
	'met.a4a': 'afs_lvt.${viewerLastVisibleTime}~afs.${time}',
	}),

Tagging a few people that were involved in the original PR @warrengm @keithwrightbos @glevitzky

Seems like the frequency has increased a bit recently. Bumping to p1 for now. The a4a team will be able to prioritize correctly.

[lannka]

It failed at here that this.analyticsGroup_ is null.

@zhouyx could you take a look if this is something to do with extension analytics.

[zhouyx]

I've definitely seen the errors before. The reason is mostly because a race condition between the analytics initialization and parent element got remove from the page. We can verify it by introducing a new param, this.hasDetached_ and check on that before proceeding. Once we can verify that's the root cause, we can then remove the new param and simply check the existence of analytics group.

One thing I don't understand is why is related to story ad? @lannka Could you explain?