`RangeError` in worker method

[muccy]

Hi,
I've found some of those errors logged in Crashlytics.

RangeError (length): Invalid value: Not in inclusive range 0..27: 28. Error thrown null.

Non-fatal Exception: FlutterError
0  ???                            0x0 JsonCodec.encode (dart:convert)
1  ???                            0x0 StorageImpl._workerMethod.<fn> + 54 (io.dart:54)
2  ???                            0x0 _EventSinkWrapper.add (dart:async)
3  ???                            0x0 IsoWorker._entryPoint.<fn> + 87 (isoworker.dart:87)

I don't understand how it could be possible to have a RangeError since I find only strings and maps, not lists. Do you have any idea? Maybe it's something bound to map intrinsic mutability and you need to make a copy of data when you pass the map to worker? (I'm just taking a shot)

Thanks a lot

[zuvola]

The log shows that the encoding of Json is failing, so I can assume that there is a problem with the data.
Even if it's only String and Map, List is used in json.encode(), so I think RangeError is being raised there.
For example, it could be that there are characters that cannot be converted to UTF8 mixed in, causing some kind of inconsistency.
If that's the case, it's a problem on the dart side.
Of course, I can't deny the possibility that the problem is on the tiny_storage side, so if you have data or code that can reproduce the error, I can investigate the cause a little more.

[muccy]

Sorry but I cannot reproduce. It's very strange because I'm using tiny_storage as an internal storage: it's masked and private and I'm saving in it only strings derived from another jsonEncode on from a base64 encoding. I don't how they can contain invalid characters

[zuvola]

Is it just Base64 strings? That's certainly strange. Please give me some time to do some more research.

[muccy]

If the problem happens on write (and not on removal) I can guarantee you that keys and values set in tiny_storage come from this function

  String _encryptedString(String src) {
    if (_encrypter == null) {
      return src;
    } else {
      final iv = IV.fromLength(16);
      return _encrypter!.encrypt(src, iv: iv).base64;
    }
  }

(_encrypter is never null, actually).

The src string is either a constant string (say "true") or a string created by another json.encode.