Centerline: Wide Channel ZigZag at end of channel

[MattReimer]

This is a tricky one that we may need to punt on for now:

Obviously the centerline is trying to exit with the thalweg which causes problems.

This is really hard to do though since we don't have a reliable way of finding the endpoint of the channel.

[MattReimer]

This is not something we are going to solve with this method. We need a better way to handle endpoints.