Implement minor fix and add changelog entry

CHANGELOG.md

@@ -60,6 +60,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (cli) [#1226](https://github.com/evmos/ethermint/pull/1226) Add custom app db backend flag.
 * (cli) [#1230](https://github.com/evmos/ethermint/pull/1230) Remove redundant positional height parameter from feemarket's query cli.
 * (test) [#1311](https://github.com/evmos/ethermint/pull/1311) add integration test for the rollback cmd
+* (ledger) [#1277](https://github.com/evmos/ethermint/pull/1277) Add Ledger preprocessing transaction hook for EIP-712-signed Cosmos payloads.
 
 ### Bug Fixes
 

ethereum/eip712/preprocess.go

@@ -37,7 +37,11 @@ func PreprocessLedgerTx(chainID string, keyType cosmoskr.KeyType, txBuilder clie
  }
 
  signature := sigs[0]
- sigBytes := signature.Data.(*signing.SingleSignatureData).Signature
+ sigData, ok := signature.Data.(*signing.SingleSignatureData)
+ if !ok {
+ return fmt.Errorf("unexpected signature type, expected SingleSignatureData")
+ }
+ sigBytes := sigData.Signature
 
  // Parse Chain ID as big.Int
  chainIDInt, err := types.ParseChainID(chainID)