Returning an empty hash in a HTTP delete results in ... | ruby-grape/grape

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After upgrading to Grape >= 0.19.1, the default status code for DELETE is now 204 instead of 200.
When returning a response which is not empty (for example {'key'=>'value'}, a 200 is returned with the correct response body.

When a non empty hash is returned on webrick (default development rails server) this goes well: the hash is returned. However, if an empty hash is provided {}, it results in an exception:

[2018-07-10 15:38:03] ERROR TypeError: no implicit conversion of Hash into String
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/handler/webrick.rb:113:in `block in service'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/body_proxy.rb:31:in `each'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/body_proxy.rb:31:in `each'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/body_proxy.rb:31:in `each'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/body_proxy.rb:31:in `each'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/body_proxy.rb:31:in `each'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/body_proxy.rb:31:in `each'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/body_proxy.rb:31:in `each'
	/Users/bas.janssen/.rvm/gems/ruby-2.4.4@rails4/gems/rack-1.6.10/lib/rack/handler/webrick.rb:112:in `service'
	/Users/bas.janssen/.rvm/rubies/ruby-2.4.4/lib/ruby/2.4.0/webrick/httpserver.rb:140:in `service'
	/Users/bas.janssen/.rvm/rubies/ruby-2.4.4/lib/ruby/2.4.0/webrick/httpserver.rb:96:in `run'
	/Users/bas.janssen/.rvm/rubies/ruby-2.4.4/lib/ruby/2.4.0/webrick/server.rb:308:in `block in start_thread'

with the following output (http 500):

<HTML>
    <HEAD>
        <TITLE>Internal Server Error</TITLE>
    </HEAD>
    <BODY>
        <H1>Internal Server Error</H1>
    no implicit conversion of Hash into String
        <HR>
        <ADDRESS>
     WEBrick/1.3.1 (Ruby/2.4.4/2018-03-28) at
     localhost:3005
    </ADDRESS>
    </BODY>
</HTML>

Adding an explicit status of 200 solves this:

delete do
  status 200
  {}
end

Is this issue known, can someone confirm this and can it be solved in some way?

Reproduce the DELETE endpoint that returns {} with the default 204 status on WEBrick, then inspect the stack locations named in rack/handler/webrick.rb and rack/body_proxy.rb. Confirm the behavior against the non-empty hash and explicit-200 cases; done means the empty response no longer raises the reported Hash-to-String exception.

Written by the indexing model from the issue text.

Returning an empty hash in a HTTP delete results in an exception

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