raw-body will hang when the param is a parsed body

[ziyofun]

Hi, thanks for your work on this repo.
I use raw-body and koa-joi-router which depends on raw-body in my project the same time.
I found that the body already parsed can not emit any listener in readStream function of raw-body even if the stream.readable is false.
It may be better if throw some error of just return the parsed body this situation.

[dougwilson]

That sounds like a good idea. Even #32 getting implemented would help here as well, since the timeout would trigger in that situation.

Do you want to make a pull request or provide code that I can run which demonstrates the issue so I can make the change?

[ziyofun]

OK, I create a PR #58 to check the validation of stream but I dont think timeout is a good solution, it maybe means more work to distinguish error and just timeout.