Crash if fetch has already decompressed the data

[ssb22]

Hi, thanks for all your work on Vosklet. I'm currently helping a charity migrate an unreleased accessibility app from vosk-browser to Vosklet (I'm using version 1.2.1 from commit c64ae47) and one quirk I found was that, at least in the environment of their app, fetch() does the gzip decompression itself so res.body.pipeThrough(new DecompressionStream('gzip')) crashes as it's trying to decompress data that has already been decompressed. For their app I'll just say patch it by removing the two calls to pipeThrough but just wanted to report this in case you want to catch "not compressed" more generally. Thanks again.

[ssb22]

fetch() always decompresses gzip if the server headers declare gzip encoding. Manual decompression might still be needed in environments where the server headers don't declare it.