Make Server non-failable again
    
    It was made failable in #382, back in 2017, as part of the
    Modular Server effort that was eventually abandoned, with the
    idea being that Modular Server would be blocking instead. But
    when Modular Server was abandoned, we never reverted this change
    to make Server non-failable again...
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>