Issues with account key migration from Gaia 2.X to Gaia 4.X

[ebuchman]

I have some keys created with Gaia 2.X.

I run:

$ cp -ar ~/.gaiacli/keys ~/.gaia
$ gaiad keys migrate

Migrate fails a couple ways.

For offline keys and ledger keys I get something like:

Error: unmarshal to types.PubKey failed after 4 bytes (unrecognized prefix bytes 028CF77D):

And for multisig I get a panic like:

panic: reflect: call of reflect.Value.Type on zero Value
goroutine 1 [running]:
reflect.Value.Type(0x0, 0x0, 0x0, 0x0, 0x0)
	reflect/value.go:1908 +0x189
github.com/tendermint/go-amino.(*Codec).MarshalBinaryBare(0xc0000ad180, 0x0, 0x0, 0x0, 0x0, 0xc000067200, 0x0, 0xc00149f3b8)
	github.com/tendermint/go-amino@v0.16.0/amino.go:201 +0x150
github.com/cosmos/cosmos-sdk/codec/types.AminoPacker.UnpackAny(0xc0000ad180, 0xc000c63980, 0x55854e0, 0xc0001a68e0, 0xc00149f418, 0x400d565)
	github.com/cosmos/cosmos-sdk@v0.41.2/codec/types/compat.go:119 +0x9b
github.com/cosmos/cosmos-sdk/crypto/keys/multisig.(*LegacyAminoPubKey).UnpackInterfaces(0xc000fe65a0, 0x5cdb500, 0xc0000ad180, 0x2ec06878, 0xc000fe65a0)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keys/multisig/multisig.go:147 +0xa6
github.com/cosmos/cosmos-sdk/codec/types.UnpackInterfaces(...)
	github.com/cosmos/cosmos-sdk@v0.41.2/codec/types/interface_registry.go:286
github.com/cosmos/cosmos-sdk/codec.(*LegacyAmino).marshalAnys(0xc000126100, 0x5833160, 0xc000fe65a0, 0x180, 0xc0000ae300)
	github.com/cosmos/cosmos-sdk@v0.41.2/codec/amino.go:65 +0x9b
github.com/cosmos/cosmos-sdk/codec.(*LegacyAmino).MarshalBinaryBare(0xc000126100, 0x5833160, 0xc000fe65a0, 0x0, 0xc00149f520, 0x4110116, 0x55d8c00, 0x16a)
	github.com/cosmos/cosmos-sdk@v0.41.2/codec/amino.go:81 +0x45
github.com/cosmos/cosmos-sdk/codec.(*LegacyAmino).MustMarshalBinaryBare(...)
	github.com/cosmos/cosmos-sdk@v0.41.2/codec/amino.go:89
github.com/cosmos/cosmos-sdk/crypto/keys/multisig.(*LegacyAminoPubKey).Bytes(0xc000fe65a0, 0x5afa338, 0xc00149f570, 0x410fa9a)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keys/multisig/multisig.go:40 +0x47
github.com/cosmos/cosmos-sdk/crypto/keys/multisig.(*LegacyAminoPubKey).Address(0xc000fe65a0, 0xc0000ae302, 0xc000c0a4b0, 0xea)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keys/multisig/multisig.go:35 +0x2f
github.com/cosmos/cosmos-sdk/crypto/keyring.offlineInfo.GetAddress(...)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keyring/info.go:172
github.com/cosmos/cosmos-sdk/crypto/keyring.keystore.existsInDb(0x5d15fe0, 0xc00001dfb0, 0xc0001af840, 0x1, 0x1, 0xc0001af850, 0x1, 0x1, 0x5d1c3f0, 0xc0000bd770, ...)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keyring/keyring.go:757 +0x49
github.com/cosmos/cosmos-sdk/crypto/keyring.keystore.writeInfo(0x5d15fe0, 0xc00001dfb0, 0xc0001af840, 0x1, 0x1, 0xc0001af850, 0x1, 0x1, 0x5d1c3f0, 0xc0000bd770, ...)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keyring/keyring.go:728 +0x1bb
github.com/cosmos/cosmos-sdk/crypto/keyring.keystore.writeOfflineKey(0x5d15fe0, 0xc00001dfb0, 0xc0001af840, 0x1, 0x1, 0xc0001af850, 0x1, 0x1, 0xc0001a2210, 0xc, ...)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keyring/keyring.go:775 +0xf0
github.com/cosmos/cosmos-sdk/crypto/keyring.keystore.ImportPubKey(0x5d15fe0, 0xc00001dfb0, 0xc0001af840, 0x1, 0x1, 0xc0001af850, 0x1, 0x1, 0xc0001a2210, 0xc, ...)
	github.com/cosmos/cosmos-sdk@v0.41.2/crypto/keyring/keyring.go:313 +0x206
github.com/cosmos/cosmos-sdk/client/keys.runMigrateCmd(0xc000f0fb80, 0xc000e59ee0, 0x0, 0x2, 0x0, 0x0)
	github.com/cosmos/cosmos-sdk@v0.41.2/client/keys/migrate.go:115 +0x6e8
github.com/spf13/cobra.(*Command).execute(0xc000f0fb80, 0xc000e59ec0, 0x2, 0x2, 0xc000f0fb80, 0xc000e59ec0)
	github.com/spf13/cobra@v1.1.3/command.go:852 +0x472
github.com/spf13/cobra.(*Command).ExecuteC(0xc000c69680, 0x0, 0x0, 0xc000db7fe0)
	github.com/spf13/cobra@v1.1.3/command.go:960 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
	github.com/spf13/cobra@v1.1.3/command.go:897
github.com/spf13/cobra.(*Command).ExecuteContext(...)
	github.com/spf13/cobra@v1.1.3/command.go:890
github.com/cosmos/cosmos-sdk/server/cmd.Execute(0xc000c69680, 0xc000db7fe0, 0x19, 0x5d2e458, 0xc000de0b70)
	github.com/cosmos/cosmos-sdk@v0.41.2/server/cmd/execute.go:36 +0x265