Early server errors can fail to log when the server is shutdown

From https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/consul-tool/EoGPwvesmT8/-GyPaCEeAAAJ it looks like the pattern of calling `s.Shutdown()` is preventing the errors from getting logged properly, making it hard to diagnose what's going on if things fail super early in `NewServer()`.

Start by tracing NewServer and the s.Shutdown() path described in the issue, focusing on what happens when initialization fails very early. Confirm the failure mode with an early NewServer error and determine what logging behavior is expected during shutdown; done means those errors are reliably logged for diagnosis.

Written by the indexing model from the issue text.