Improve error messages for APDU_CODE_BAD_KEY_HANDLE

user_app.go

@@ -274,6 +274,19 @@ func (ledger *LedgerCosmos) sign(instruction byte, bip32Path []uint32, transacti
 
 		response, err := ledger.api.Exchange(message)
 		if err != nil {
+			if err.Error() == "[APDU_CODE_BAD_KEY_HANDLE] The parameters in the data field are incorrect" {
+				// In this special case, we can extract additional info
+				errorMsg := string(response)
+				switch errorMsg {
+				case "ERROR: JSMN_ERROR_NOMEM":
+					return nil, fmt.Errorf("Not enough tokens were provided");
+				case "PARSER ERROR: JSMN_ERROR_INVAL":
+					return nil, fmt.Errorf("Unexpected character in JSON string");
+				case "PARSER ERROR: JSMN_ERROR_PART":
+					return nil, fmt.Errorf("The JSON string is not a complete.");
+				}
+				return nil, fmt.Errorf(errorMsg)
+			}
 			return nil, err
 		}
 

user_app_test.go

@@ -219,3 +219,22 @@ func Test_UserSign(t *testing.T) {
 		return
 	}
 }
+
+func Test_UserSign_Fails(t *testing.T) {
+	userApp, err := FindLedgerCosmosUserApp()
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	defer userApp.Close()
+
+	userApp.api.Logging = true
+
+	path := []uint32{44, 118, 0, 0, 5}
+
+	message := getDummyTx()
+	garbage := []byte{65}
+	message = append(garbage, message...)
+
+	_, err = userApp.SignSECP256K1(path, message)
+	assert.EqualError(t, err, "Unexpected character in JSON string")
+}