module Byebug

end
...
offender
...
Byebug.post_mortem do
end
raise 'error'
def offender

e.g.
enable post-mortem mode by wrapping this block with Byebug.post_mortem,
If you know that a particular block of code raises an exception you can

== Local post-mortem mode

and enables post-mortem mode.
at_exit hook that intercepts any exception not handled by your script
By calling Byebug.post_mortem method without a block, you install an
== Global post-mortem mode

Activates the post-mortem mode. There are two ways of using it:
#

def post_mortem
  if block_given?
    old_post_mortem = self.post_mortem?
    begin
      self.post_mortem = true
      yield
    rescue Exception => exp
      handle_post_mortem(exp)
      raise
    ensure
      self.post_mortem = old_post_mortem
    end
  else
    return if self.post_mortem?
    self.post_mortem = true
    debug_at_exit do
      handle_post_mortem($!) if $! && post_mortem?
    end
  end
end