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wizzard

repeat-keys

[wizzard] repeat keys collide in group "<id>": "<key>" at <i> and <j>. …
[wizzard] item <i> of repeat group "<id>" has no key at "<keyBy>". …

Returned, not thrown: the move answers { ok: false, reason: 'invalid' } with the group as by and the message under the keyBy field, so a binding displays it exactly where it displays a validation error.

A repeat frame stores the item’s key and nothing else - never its index, which moves when the list is reordered and dangles when an item is removed. So the key has to identify one item, and two conditions stop it doing that:

  • Collision. Keys are compared as strings, so 1 and '1' are one key, and every object without a distinguishing keyBy reads as [object Object]. A frame naming a duplicated key could mean either item.
  • No identity. undefined, null and '' name no item.

Both are data errors, and both are refused rather than resolved: falling back to the position is exactly the stale-position bug that keying by identity exists to remove. Selectors keep working while the data is wrong - a colliding key binds to the first item that carries it - so the screen stays rendered and the move is what refuses.

The fix is to make keyBy unique and present across the items, or to drop keyBy and accept positional identity, where reordering the list moves the answers with the position rather than with the item.