🚨 Error: b.signals is not a function

Details
---
**Error report:** [link](http://go/ampe/CICqqefz1ebrswE)
**First seen:** May 2, 2019
**Frequency:** ~ 2,824/day

Stacktrace
---

Error: b.signals is not a function

    at signals (extensions/amp-image-viewer/0.1/amp-image-viewer.js:182:8)

    at layoutCallback (src/custom-element.js:1625:50)

    at src/core/data-structures/promise.js:82:12

    at src/core/data-structures/promise.js:81:9

    at tryResolve (src/custom-element.js:1625:22)

    at layoutCallback (src/service/resource.js:897:40)

    at ret (src/service/vsync-impl.js:468:16)

    at callTask_ (src/service/vsync-impl.js:425:8)

Notes
---
`@kristoferbaxter` modified `extensions/amp-image-viewer/0.1/amp-image-viewer.js:182-182` in [#34028](https://github.com/ampproject/amphtml/pull/34028) (May 20, 2021)
`@jridgewell` modified `src/core/data-structures/promise.js:82-85` in [#15143](https://github.com/ampproject/amphtml/pull/15143) (May 8, 2018)
`@renovate-bot` modified `src/core/data-structures/promise.js:81-81` in [#27350](https://github.com/ampproject/amphtml/pull/27350) (Mar 30, 2020)
`@dvoytenko` modified `src/custom-element.js:1625-1625` in [#32345](https://github.com/ampproject/amphtml/pull/32345) (Feb 4, 2021)
`@dvoytenko` modified `src/service/resource.js:897-897` in [#32099](https://github.com/ampproject/amphtml/pull/32099) (Jan 21, 2021)
`@jridgewell` modified `src/service/vsync-impl.js:468-469` in [#20836](https://github.com/ampproject/amphtml/pull/20836) (Feb 14, 2019)
`@rsimha` modified `src/service/vsync-impl.js:425-425` in [#23363](https://github.com/ampproject/amphtml/pull/23363) (Jul 17, 2019)

**Seen in:**
- 05-21 Nightly (0438)

/cc @ampproject/release-on-duty