ConsensusContext.HandleMessage() creates context with earlier validator set

[OnedgeLee]

If ConsensusContext receives a message with higher height than current height, it tries to create a new Context with height of received message via ConsensusContext.CreateContext().

libplanet/Libplanet.Net/Consensus/ConsensusContext.cs

Lines 250 to 253 in 690a98c

	if (!_contexts.ContainsKey(height))
	{
	_contexts[height] = CreateContext(height);
	}

But ConsensusContext.CreateContext() creates Context with validator set of ConsensusContext.Height - 1, so validator set of created Context is different from actual one, if ConsensusMessage.Height != ConsensusContext.Height.

libplanet/Libplanet.Net/Consensus/ConsensusContext.cs

Lines 442 to 444 in 690a98c

	_blockChain
	.GetWorldState(_blockChain[Height - 1].Hash)
	.GetValidatorSet(),

It does not make any critical problems if validator set is static, but when it varies, can be a matter.

Since Context cannot be generated without validator set, and validator set cannot be decided without actual block appending, Context should not be created through this path, IMO.

[OnedgeLee]

For Context, ValidatorSet does not needed, since it has BlockChain, also.
Removing ValidatorSet field and replacing them with BlockChain[Height].GetValidatorSet() would resolve this problem.