don't stomp bodies in `halt` unless a body arg is given

[nweathersbee]

See

deas/lib/deas/runner.rb

Line 72 in 9f7415c

self.body(args.shift)

It is always overwriting body, even if there was already a body specified. It needs to only call the body method if the last optional arg (which would be the body) is given (ie not nil).

This is preventing code like this from working:

    rescue ActiveRecord::RecordNotFound
      body "Unknown company #{company_slug.inspect}."
      halt 422

The workaround you have to do for now is:

    rescue ActiveRecord::RecordNotFound
      halt 422, {}, "Unknown company #{company_slug.inspect}."