Function read_frame_json 

pub async fn read_frame_json<R, T>(r: &mut R) -> Result<Option<T>, FrameError>
where
    R: AsyncRead + Unpin,
    T: DeserializeOwned,

Read a framed JSON blob and decode into T. Returns Ok(None) on a clean frame-boundary EOF.

Errors

Returns FrameError::Io for frame transport failures and FrameError::Json when the frame body cannot be decoded as T.