For `Random.nextInt(int max)`, `max` is exclusive (https://api.dart.dev/stable/2.14.4/dart-math/Random/nextInt.html). This means the `_randomBytes()` function (https://github.com/dart-bitcoin/bitcoin_flutter/blob/master/lib/src/ecpair.dart#L92) does not include 255. `_SIZE_BYTE` should be 256.
For
Random.nextInt(int max),maxis exclusive (https://api.dart.dev/stable/2.14.4/dart-math/Random/nextInt.html). This means the_randomBytes()function (https://github.com/dart-bitcoin/bitcoin_flutter/blob/master/lib/src/ecpair.dart#L92) does not include 255._SIZE_BYTEshould be 256.