httpuv claims to handle NULL body

[nteetor]

Line 202 of httpuv/httpuv.cpp claims that NULL is valid value for "body" in the list returned by $call(). However, I know this is not true, for one reason or another. See the below example,

demo_app <- list(
  call = function(req) {
    if (req$PATH_INFO == '/null_body') {
      list(
        status = 200L,
        headers = list(
          'Connection' = 'close'
        ),
        body = NULL
      )
    } else {
      list(
        status = 404L,
        headers = list(
          'Content-Type' = 'text/plain'
        ),
        body = paste(req$PATH_INFO, 'not found')
      )
    }
  }
)

httpuv::runServer('127.0.0.1', 3030, demo_app)

If you navigate to localhost:3030/null_body the httpuv server will crash with an Rcpp error. I have not raised an httpuv issue yet as I do not have the location of the bug. Once I can confirm this is truly an httpuv issue I will raise an issue with httpuv.

Although I have been working around this bug for some time, I raise this issue now because I just came across httpuv's claim on line 202.