🚨 Error: undefined is not a function

Details
---
**Error report:** [link](http://go/ampe/CO_SnMWHwvnyTQ)
**First seen:** Apr 13, 2022
**Frequency:** ~ 33,636/day

Stacktrace
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Error: undefined is not a function

    at forEach (extensions/amp-story/1.0/amp-story-grid-layer.js:111:28)

    at setDescendentCssGridStyles_ (extensions/amp-story/1.0/amp-story-grid-layer.js:82:9)

    at buildCallback (src/custom-element.js:549:30)

Notes
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`@alanorozco` modified `extensions/amp-story/1.0/amp-story-grid-layer.js:111-111` in [#38004](https://github.com/ampproject/amphtml/pull/38004) (Apr 4, 2022)
`@newmuis` modified `extensions/amp-story/1.0/amp-story-grid-layer.js:81-82` in [#11487](https://github.com/ampproject/amphtml/pull/11487) (Oct 2, 2017)
`@dvoytenko` modified `src/custom-element.js:539-553` in [#32568](https://github.com/ampproject/amphtml/pull/32568) (Feb 25, 2021)

**Seen in:**
- 04-22 Control (1712)
- 04-22 Stable (1712)
- 04-29 Beta (2129)
- 04-29 Experiment-B (2129)
- 04-29 Experimental (2129)
- +1 more

**Possible assignees:** `@alanorozco`, `@dvoytenko`

/cc @ampproject/release-on-duty