App fails with: nlohmann::json_abi_v3_11_2::detail::type_error

[tomekit]

We're affected by the libjson replacement with https://github.com/nlohmann/json in this commit: https://github.com/mogol/flutter_secure_storage/commit/647a5d1035444959dc9c3034a78a13154493b2dc

Below code

final random = Random();
final intRandom = random.nextInt(100000000);
final secureStorage = SecureStorage();
await secureStorage.write(key: 'testKey', value: intRandom.toString());
final readInt = await secureStorage.read(key: 'testKey');
context.showSnackBar(message: "Generated: ${intRandom.toString()}; Read after save: ${readInt.toString()}");

crashes the app, with below error:

terminate called after throwing an instance of 'nlohmann::json_abi_v3_11_2::detail::type_error'
  what():  [json.exception.type_error.307] cannot use erase() with null

We can't reproduce it on the machine that we compile the code on, however once we pass code to another machine, e.g. using Flathub format: https://github.com/flathub/io.kapsa.drive/blob/master/io.kapsa.drive.json#L252 we get this error.

Our solution was to revert this commit in our fork: https://github.com/Mino5531/flutter_secure_storage/compare/develop...tomekit:flutter_secure_storage:develop

and load it like this:

dependencies:
  flutter_secure_storage:
    git:
      url: https://github.com/tomekit/flutter_secure_storage.git
      ref: develop
      path: flutter_secure_storage
dependency_overrides:
  flutter_secure_storage_linux:
    git:
      url: https://github.com/tomekit/flutter_secure_storage.git
      ref: develop
      path: flutter_secure_storage_linux

Do you have an idea why this error may occur on some machines?

Out of curiosity what was the reason of moving away from libjsoncpp25?

[robertolaru]

I am experiencing the same error:

terminate called after throwing an instance of 'nlohmann::json_abi_v3_11_2::detail::type_error'
  what():  [json.exception.type_error.307] cannot use erase() with null
Lost connection to device.

I am using flutter_secure_storage: ^9.0.0

[AdivonSlav]

Also experiencing the same issue with the same error on version 9.0.0

[Nightwelf]

Hi! I fix this problem like this

final data = await _flutterSecureStorage?.read(key: 'myKey');
if(data != null) {
    await _flutterSecureStorage?.delete(key: 'myKey');
}

[tmaegel]

Hi! I fix this problem like this

final data = await _flutterSecureStorage?.read(key: 'myKey');
if(data != null) {
    await _flutterSecureStorage?.delete(key: 'myKey');
}

Thank you. That solved the problem for me.

[tomekit]

Bear in mind that if you have multiple processes reading/updating this key simultaneously given other bugs like (https://github.com/mogol/flutter_secure_storage/issues/592) you might end up with inconsistent results.

[Nightwelf]

Bear in mind that if you have multiple processes reading/updating this key simultaneously given other bugs like (#592) you might end up with inconsistent results.

thanks