AccessViolationException when receiving a PermissionDenied error

[nirinchev]

#3259 introduced a bug in the way we deserialize the userInfo that results in the following crash:

Fatal error. System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
   at System.String.GetNonRandomizedHashCode()
   at System.Collections.Generic.Dictionary`2[[System.__Canon, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.__Canon, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].TryInsert(System.__Canon, System.__Canon, System.Collections.Generic.InsertionBehavior)
   at System.Linq.Enumerable.ToDictionary[[Realms.Sync.Native.StringStringPair, Realm, Version=10.21.0.0, Culture=neutral, PublicKeyToken=null],[System.__Canon, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.__Canon, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.Collections.Generic.IEnumerable`1<Realms.Sync.Native.StringStringPair>, System.Func`2<Realms.Sync.Native.StringStringPair,System.__Canon>, System.Func`2<Realms.Sync.Native.StringStringPair,System.__Canon>, System.Collections.Generic.IEqualityComparer`1<System.__Canon>)
   at System.Linq.Enumerable.ToDictionary[[Realms.Sync.Native.StringStringPair, Realm, Version=10.21.0.0, Culture=neutral, PublicKeyToken=null],[System.__Canon, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.__Canon, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](System.Collections.Generic.IEnumerable`1<Realms.Sync.Native.StringStringPair>, System.Func`2<Realms.Sync.Native.StringStringPair,System.__Canon>, System.Func`2<Realms.Sync.Native.StringStringPair,System.__Canon>)
   at Realms.Sync.SessionHandle.HandleSessionError(IntPtr, Realms.Native.SyncError, IntPtr)

We should backport this and release 10.21.1.