requestUnvault() started, named
by the vault request’s id. The wallet fetches the prepared cancel, sends it
with the cost covered by Endstate, and resolves once the network has included
it. The vault request reads active again once Endstate sees it, and the item
stays vaulted. Only a wallet that holds the item now can send it.
The owner can cancel while the unvault waits, including while it is on hold.
Once the item is ready to ship the call rejects with
submission.not_executable, and error.details.cancellable_at is the time a
cancel opens again if the vault has not dispatched the item: 7 days after the
waiting period ended. It is present only while the item is ready to ship and
not dispatched. After the vault’s dispatch the unvault can no longer be
cancelled, and the error carries no cancellable_at.
Also rejects with submission.not_executable when no unvault is waiting,
with vault.request_not_found when the id names no vaulted item, with
auth.forbidden when this wallet does not hold the item, with
wallet.sponsorship_unavailable when the send cannot be covered right now
(nothing was sent), and with wallet.destroyed if the wallet has been
destroyed.
Rejects with wallet.unsupported_operation when the wallet frame Endstate
runs is older than this SDK and does not know the operation yet. Nothing was
sent. The error’s message says to upgrade the SDK, which does not apply here:
the SDK is already the newer side, so retry once the frame is updated.

