A wallet that holds a contract's key but cannot sign with it: a watch-only
identity, or a remote signer whose transport is absent.
Distinct from ForeignDescriptorError because the remedy differs —
that one says "wrong wallet", this one says "this wallet, without its
signer". Raised at provisioning as well as at signing, so a wallet that
could never spend the leg finds out before it funds one.
A wallet that holds a contract's key but cannot sign with it: a watch-only identity, or a remote signer whose transport is absent.
Distinct from ForeignDescriptorError because the remedy differs — that one says "wrong wallet", this one says "this wallet, without its signer". Raised at provisioning as well as at signing, so a wallet that could never spend the leg finds out before it funds one.