Null pointer exception when body is not present in the request

[subnetmarco]

The following error occurs for requests that don't present a body, like a 100-continue request for multipart-data reqs.

2015/09/23 09:08:29 [error] 3927#0: *10985 lua entry thread aborted: runtime error: /usr/local/share/lua/5.1/multipart.lua:42: attempt to index local 'body' (a nil value)
stack traceback:
coroutine 0:
        /usr/local/share/lua/5.1/multipart.lua: in function 'decode'
        /usr/local/share/lua/5.1/multipart.lua:110: in function 'Multipart'
        /usr/local/share/lua/5.1/kong/plugins/keyauth/access.lua:48: in function 'get_key_from_query'
        /usr/local/share/lua/5.1/kong/plugins/keyauth/access.lua:108: in function </usr/local/share/lua/5.1/kong/plugins/keyauth/access.lua:103>
        /usr/local/share/lua/5.1/kong/plugins/keyauth/access.lua:123: in function 'execute'
        /usr/local/share/lua/5.1/kong/plugins/keyauth/handler.lua:12: in function 'access'
        /usr/local/share/lua/5.1/kong.lua:191: in function 'exec_plugins_access'
        access_by_lua(nginx.conf:89):1: in function <access_by_lua(nginx.conf:89):1>, client: xxx.xxx.xxx.xxx, server: _, request: "POST /api/v1/ HTTP/1.1", host: "kong.<Domain>:8000"
2015/09/23 09:08:29 [error] 3927#0: *10985 [lua] responses.lua:61: send_HTTP_INTERNAL_SERVER_ERROR(): An unexpected error occurred, client: xxx.xxx.xxx.xxx, server: _, request: "POST /api/v1/ HTTP/1.1", host: "kong.<Domain>:8000"