Bug: Not handling all cases

[xpepermint]

I've been testing this library using nghttp CLI and notice it doesn't handle all cases well. I noticed that nghttp randomly sends a HEADER frame where 3 bits are missing in the middle of a frame. This is so strange, and I can not reproduce it in a way that I'd be able to write the instructions. I switched to another HPACK implementation and it worked so I guess more tests are needed for this library to be production-ready. Sorry for a vague explanation, I hope it helps anyway.

# Example: Run this multiple times
$ nghttp -nva --data test.mp4 http://127.0.0.1:8080