Error handling

BmoniSignerException codes and how to handle them.

All SDK failures surface as a BmoniSignerException carrying:

• errorCode — a BmoniSignerErrorCode enum value for programmatic branching
• message — a human-readable description

try {
  await BmoniEmbeddedSdk.initWallet();
} on BmoniSignerException catch (e) {
  print('Code: ${e.errorCode}');   // BmoniSignerErrorCode.walletAlreadyExists
  print('Message: ${e.message}');  // "A wallet already exists on this device."
}

---

Error codes

Signing errors (0x3001xxxx)

Originate inside the native BMONISigner SDK.

Constant	Hex	When it is thrown
walletAlreadyExists	0x30010010	initWallet called while a wallet is already stored on disk.
signInvalidMessage	0x30010001	The supplied message could not be processed.
signInvalidPrivateKey	0x30010002	The stored key could not be recovered or decrypted.
signInvalidHash	0x30010003	The hash argument was not a valid 0x-prefixed 32-byte hex string.
signProcess	0x30010004	Generic ECDSA signing failure.
signKeygen	0x30010005	secp256k1 keypair generation failed.
signEip55	0x30010006	EIP-55 checksum derivation failed.

PIN errors (0x4xxxxxxx)

Generated by the Dart-layer PIN gate.

Constant	Hex	When it is thrown
pinNotSet	0x40000001	A PIN-gated call was attempted but no PIN has been set.
pinAlreadySet	0x40000002	setPin called while a PIN already exists — use changePin instead.
pinMismatch	0x40000003	The supplied PIN did not match the stored digest.
pinInvalid	0x40000004	The supplied PIN was empty, the wrong length, or otherwise invalid.

Bridge errors (0x5xxxxxxx)

Generated by the Dart method-channel bridge.

Constant	Hex	When it is thrown
unexpectedNativeNull	0x50000001	A native method that promised a non-null result returned null — indicates a plugin-bridge bug.

---

Handling the most common cases

Future<void> handleSigningFlow() async {
  try {
    final String sig = await BmoniEmbeddedSdk.signMessage(
      'Hello',
      pin: userEnteredPin,
    );
    onSuccess(sig);
  } on BmoniSignerException catch (e) {
    switch (e.errorCode) {
      case BmoniSignerErrorCode.pinNotSet:
        // Redirect the user to the PIN setup flow.
        break;
      case BmoniSignerErrorCode.pinMismatch:
        // Ask the user to re-enter their PIN.
        break;
      case BmoniSignerErrorCode.pinInvalid:
        // PIN was the wrong length or empty.
        break;
      case BmoniSignerErrorCode.walletAlreadyExists:
        // Only thrown by initWallet — show a re-provision dialog.
        break;
      default:
        // Native or bridge error — log and show a generic message.
        debugPrint('Unexpected SDK error: ${e.message} (${e.errorCode})');
    }
  }
}

---

PlatformException

In rare cases the method channel itself may throw a Flutter PlatformException. These are distinct from BmoniSignerException and typically indicate a misconfigured platform environment:

import 'package:flutter/services.dart';

try {
  await BmoniEmbeddedSdk.initWallet();
} on BmoniSignerException catch (e) {
  // SDK-level error
} on PlatformException catch (e) {
  debugPrint('Platform error: ${e.message ?? e.code}');
}