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a8a50f32f5
The bug manifests when a nil ChannelType is passed to the funding manager in InitFundingMsg. A default value for ChannelType is selected and sent in the OpenChannel message. However, a nil ChannelType is stored in the reservation context. This causes our ChannelType checks in handleFundingAccept to be bypassed. Usually this makes us end up in the "peer unexpectedly sent explicit ChannelType" case, where we can still recover by reselecting a default ChannelType and verifying it matches the one the peer sent. But if the peer sends a nil ChannelType, we miss it. While fixing the bug, I also tried to simplify the negotiation logic, as the complexity is likely what hid the bug in the first place. Now negotiateCommitmentType only returns the ChannelType to be used in OpenChannel/AcceptChannel and the CommitmentType to pass to the wallet. It will even return a nil ChannelType when we're supposed to use implicit negotiation, so we don't need to manually set it to nil for OpenChannel and AcceptChannel.