You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: error.rs
    path of file: ./repos/phaser/phaser/vendor/h2/src/codec
    
    the code of the file until where you have to start completion: use crate::proto::Error;

use std::{error, fmt, io};

/// Errors caused by sending a message

    
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        use self::UserError::*;

        fmt.write_str(match *self {
            InactiveStreamId => "inactive stream",
            UnexpectedFrameType => "unexpected frame type",
            PayloadTooBig => "payload too big",
            Rejected => "rejected",
            ReleaseCapacityTooBig => "release capacity too big",
            OverflowedStreamId => "stream ID overflowed",
            MalformedHeaders => "malformed headers",
            MissingUriSchemeAndAuthority => "request URI missing scheme and authority",
            PollResetAfterSendResponse => "poll_reset after send_response is illegal",
            SendPingWhilePending => "send_ping before received previous pong",
            SendSettingsWhilePending => "sending SETTINGS before received previous ACK",
            PeerDisabledServerPush => "sending PUSH_PROMISE to peer who disabled server push",
        })
    }