## Summary
Fixes#18413 - Empty chunked gzip responses were causing `Decompression
error: ShortRead`
## The Issue
When a server sends an empty response with `Content-Encoding: gzip` and
`Transfer-Encoding: chunked`, Bun was throwing a `ShortRead` error. This
occurred because the code was checking if `avail_in == 0` (no input
data) and immediately returning an error, without attempting to
decompress what could be a valid empty gzip stream.
## The Fix
Instead of checking `avail_in == 0` before calling `inflate()`, we now:
1. Always call `inflate()` even when `avail_in == 0`
2. Check the return code from `inflate()`
3. If it returns `BufError` with `avail_in == 0`, then we truly need
more data and return `ShortRead`
4. If it returns `StreamEnd`, it was a valid empty gzip stream and we
finish successfully
This approach correctly distinguishes between "no data yet" and "valid
empty gzip stream".
## Why This Works
- A valid empty gzip stream still has headers and trailers (~20 bytes)
- The zlib `inflate()` function can handle empty streams correctly
- `BufError` with `avail_in == 0` specifically means "need more input
data"
## Test Plan
✅ Added regression test in `test/regression/issue/18413.test.ts`
covering:
- Empty chunked gzip response
- Empty non-chunked gzip response
- Empty chunked response without gzip
✅ Verified all existing gzip-related tests still pass
✅ Tested with the original failing case from the issue
🤖 Generated with [Claude Code](https://claude.ai/code)
---------
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Ciro Spaciari <ciro.spaciari@gmail.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
