Deno panickes serving some HTTP requests with Deno.serve().

[oscarotero]

It happens with Deno 1.38.2 (macOS)
Deno 1.38.1 works fine.

This is the full backtrace:

============================================================
Deno has panicked. This is a bug in Deno. Please report this
at https://github.com/denoland/deno/issues/new.
If you can reliably reproduce this panic, include the
reproduction steps and re-run with the RUST_BACKTRACE=1 env
var set and include the backtrace in your report.

Platform: macos x86_64
Version: 1.38.2
Args: ["/Users/oscarotero/.deno/bin/deno", "run", "--unstable", "-A", "-", "-s"]

thread 'main' panicked at ext/http/service.rs:255:5:
HTTP state error: Expected to be last strong reference
stack backtrace:
   0:        0x103f65cf1 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h65343ad3a85b4e34
   1:        0x1030b2cbb - core::fmt::write::h11839d3825cb5605
   2:        0x103f3277e - std::io::Write::write_fmt::h3ab12d369399333c
   3:        0x103f6b589 - std::sys_common::backtrace::print::h405f7c76ca12eb27
   4:        0x103f6b1b5 - std::panicking::default_hook::{{closure}}::hed87c355606e1822
   5:        0x103f6ae7f - std::panicking::default_hook::hdf696ec8ea0d65aa
   6:        0x102f15b9d - deno::setup_panic_hook::{{closure}}::h7cfd1dfb3b898f8e
   7:        0x103f6be79 - std::panicking::rust_panic_with_hook::h7c5059af1af54377
   8:        0x103f6bc07 - std::panicking::begin_panic_handler::{{closure}}::hd658b0e1cffe3d4d
   9:        0x103f6bb99 - std::sys_common::backtrace::__rust_end_short_backtrace::h3d7834d0cea60a50
  10:        0x103f6bb82 - _rust_begin_unwind
  11:        0x105604123 - core::panicking::panic_fmt::ha9964785de0afb40
  12:        0x103464c07 - deno_http::service::HttpRecord::recycle::h18b58f156186a7c9
  13:        0x10350a9b6 - <futures_util::future::future::Map<Fut,F> as core::future::future::Future>::poll::hdd029f411d3bf98f
  14:        0x103509735 - deno_http::http_next::op_http_set_response_body_resource::v8_fn_ptr::h243bdcfe07ad50e4

[mmastrac]

@oscarotero Thanks for the report. Does your response handler return a stream in this case? (ie: a file, or a streaming response from fresh, etc)

Is it happening when you refresh in the browser?

[mmastrac]

I can reproduce this by dropping a TCP connection before the response is returned.

[oscarotero]

@mmastrac I don't know. I'm serving a complete site with html files, images, etc. I couldn't tell which of these responses causes the panick.