Android storage fix

[PiotrMitkowski]

FlutterSecureStorage raises an exception on some newer Android OS versions, especially when running on Pixels. Here's an example of exception from Pixel 6 with Android 12 - it's raised when OAuth2Helper tries to access the token:

Non-fatal Exception: io.flutter.plugins.firebase.crashlytics.FlutterError: PlatformException(Exception encountered, read, javax.crypto.BadPaddingException: error:1e000065:Cipher functions:OPENSSL_internal:BAD_DECRYPT
	at com.android.org.conscrypt.NativeCrypto.EVP_CipherFinal_ex(Native Method)
	at com.android.org.conscrypt.OpenSSLEvpCipher.doFinalInternal(OpenSSLEvpCipher.java:152)
	at com.android.org.conscrypt.OpenSSLCipher.engineDoFinal(OpenSSLCipher.java:374)
	at javax.crypto.Cipher.doFinal(Cipher.java:2055)
	at t6.b.b(Unknown Source:30)
	at s6.d.m(Unknown Source:11)
	at s6.d.t(Unknown Source:10)
	at s6.d.f(Unknown Source:0)
	at s6.d$b.run(Unknown Source:244)
	at android.os.Handler.handleCallback(Handler.java:938)
	at android.os.Handler.dispatchMessage(Handler.java:99)
	at android.os.Looper.loopOnce(Looper.java:201)
	at android.os.Looper.loop(Looper.java:288)
	at android.os.HandlerThread.run(HandlerThread.java:67)
, null). Error thrown null.
       at StandardMethodCodec.decodeEnvelope(message_codecs.dart:607)
       at MethodChannel._invokeMethod(platform_channel.dart:167)
       at SecureStorage.read(secure_storage.dart:14)
       at TokenStorage.getToken(token_storage.dart:25)
       at OAuth2Helper.getTokenFromStorage(oauth2_helper.dart:116)

There's a recommended fix under an issue in flutter_secure_storage repository, regarding the same problem: mogol/flutter_secure_storage#161 (comment). This PR applies the fix to oauth2_client

[okrad]

Thank you @PiotrMitkowski!

[maxhelskens]

I still have problems with the flutter_secure_storage on some android devices.

PlatformException(Exception encountered, read, java.lang.NullPointerException: Attempt to invoke interface method 'boolean android.content.SharedPreferences.contains(java.lang.String)' on a null object reference at c5.a.b(Unknown Source:5) at c5.e$b.run(Unknown Source:221) at android.os.Handler.handleCallback(Handler.java:883) at android.os.Handler.dispatchMessage(Handler.java:100) at android.os.Looper.loop(Looper.java:224) at android.os.HandlerThread.run(HandlerThread.java:67) , null). Error thrown Error while authenticating.

There's a recommended fix under an issue in flutter_secure_storage repository, regarding the same problem:
mogol/flutter_secure_storage#380 (comment)

I'll have to downgrade this package for now since it blocks certain users from using my app.

[okrad]

HI @maxhelskens, thank you, looks like the latest FlutterSecureStorage release fixes that issue.
I'll update the package asap!

[okrad]

@maxhelskens, I just published the new release with the updated dependencies. Can you check it out and see if your issue is solved?