[6.x] Bard: Adding a Bard set fails with "Something went wrong"

[o1y]

Bug description

When adding a set in Bard this fails with a really generic toast "Something went wrong" - nothing is logged in the console.

The response from the server returned 200.

The actual JS error seems to be swallowed by the catch block, which made debugging difficult. After temporarily modifying the catch to log the error this reveals:

ReferenceError: index is not defined at addSet (BardFieldtype.vue:495)

When you try to add a Bard set in a replicator you'll get

Uncaught TypeError: can't access property "[set_handle]", this.meta.defaults is undefined

How to reproduce

Add a Set in Bard

Logs

Environment

v6.0.0-beta.5

Installation

Fresh statamic/statamic site via CLI

Additional details

No response