exception on session close: thread 'main' panicked at 'called Option::unwrap() on a None value',

[cgrzemba]

I do my first steps with Rust and Rabbitmq. I try to implement a simple RPC client like described at https://www.rabbitmq.com/tutorials/tutorial-six-python.html

So far it works but it panic's at the last instruction:

session.close(200, "Bye");

with trace:

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', /home/grzemba/.cargo/registry/src/github.com-1ecc6299db9ec823/amqp-0.1.3/src/session.rs:241:48
stack backtrace:
   0:          0x102993c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hc3687c223297c054
   1:          0x106ce3c - core::fmt::write::h490009db94d7bf18
   2:          0x1012544 - std::io::Write::write_fmt::h604b90bda64bdf48
   3:           0xffd1b2 - std::panicking::default_hook::{{closure}}::hc949c290ca8c65e8
   4:           0xffce7f - std::panicking::default_hook::h6fae44f0226862fc
   5:           0xffd8ab - std::panicking::rust_panic_with_hook::h9db8509893535d48
   6:           0xffd4a5 - rust_begin_unwind
   7:          0x106ab80 - core::panicking::panic_fmt::h7014057c756aa717
   8:          0x106aacc - core::panicking::panic::hf00692194d6c54ee
   9:           0x98e1d2 - core::option::Option<T>::unwrap::hf68b7fe6e26d92cb
                               at /jenkins/jobs/oi-userland/workspace/components/developer/rust/build/amd64/src/libcore/macros/mod.rs:34
  10:           0x989441 - amqp::session::Session::close::h2f64a2ba0f51b397
                               at /home/grzemba/.cargo/registry/src/github.com-1ecc6299db9ec823/amqp-0.1.3/src/session.rs:241
  11:           0x98d23b - sync_send::main::hd6da51f102580f06
                               at src/main.rs:86
  12:           0x98443b - std::rt::lang_start::{{closure}}::h71447e2d4de10a11
                               at /jenkins/jobs/oi-userland/workspace/components/developer/rust/build/amd64/src/libstd/rt.rs:67
  13:          0x103275a - std::rt::lang_start_internal::hb6c875f54fd680ac
  14:           0x984416 - std::rt::lang_start::ha253d3ac3ad929fa
                               at /jenkins/jobs/oi-userland/workspace/components/developer/rust/build/amd64/src/libstd/rt.rs:67
  15:           0x98d45a - main
  16:           0x981737 - _start_crt
  17:           0x981698 - _start