fixes a critical bug in challengeAfter implementation. Previously it allowed an exit to be challenged by any subsequent spend. That is a broken game, as an adversary can generate an invalid future spend of a coin and invalidate that user's exits. testExploit.js in the first commit can be run to validate that the exploit is valid. later commits fix the issue.
fixes a critical bug in
challengeAfterimplementation. Previously it allowed an exit to be challenged by any subsequent spend. That is a broken game, as an adversary can generate an invalid future spend of a coin and invalidate that user's exits.testExploit.jsin the first commit can be run to validate that the exploit is valid. later commits fix the issue.