JS errors with replicator fields in v5.6.0

[heidkaemper]

Bug description

After updating to Statamic 5.6.0 replicator fields throw an JavaScript error "Cannot read properties of undefined (reading 'length')"

In some cases, this causes the entry not to be saved. The Request fails with error 422 (Unprocessable Content).

Reverting back to v5.5 fixes this.

How to reproduce

• Add a replicator field with some sets to a blueprint
• Create an entry based on that blueprint
• Add a new set
• Check the JavaScript console for errors

Logs

No response

Environment

Environment
Application Name: CHANGE_ME
Laravel Version: 11.9.1
PHP Version: 8.3.7
Composer Version: 2.7.1
Environment: local
Debug Mode: ENABLED
URL: tpl-statamic.heidkaemper.nds-dev.de
Maintenance Mode: OFF

Cache
Config: NOT CACHED
Events: NOT CACHED
Routes: NOT CACHED
Views: CACHED

Drivers
Broadcasting: null
Cache: statamic
Database: sqlite
Logs: debug / single
Mail: sendmail
Queue: sync
Session: file

Statamic
Addons: 4
Sites: 1
Stache Watcher: Enabled
Static Caching: Disabled
Version: 5.6.0 PRO

Statamic Addons
heidkaemper/statamic-toolbar: 1.2.0
ndx/statamic-bard-color-picker: 1.3.0
spatie/statamic-responsive-images: 5.0.0
stillat/antlers-components: 2.2.0

Installation

Other (please explain)

Additional details

No response