DecompressorWriter sometimes panics on drop if the input is invalid brotli

[jyn514]

This is similar to #13, but not caused by a misuse of the API, it can happen whenever the input is invalid.

The only times it doesn't happen is when the error isn't reported at all (#20).

; cat examples/compress.rs 
use std::io::{self, Write};

fn main() {
    let compressed = b"xxxxxxxxxxx";
    if let Err(e) = brotli_decompressor::writer::DecompressorWriter::new(io::stdout(), 1024).write(compressed) {
        eprintln!("{}", e);
    }
}
; cargo run --example compress -q; echo $?
Invalid Data
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', /home/jnelson/work/rust-brotli-decompressor/src/writer.rs:260:88
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
101

[danielrh]

Thanks for the report! Fixed in 092aa00