Segfault

[wavexx]

I suspect the following was generated when exiting X11 (see #67) , but I cannot be certain.
I've noticed this core file a few days ago:

Core was generated by `xidlehook --not-when-fullscreen --socket /tmp/xidlehook.sock --t'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000561230bb4f83 in xcb::xproto::<impl xcb::base::Reply<xcb::ffi::xproto::xcb_get_window_attributes_reply_t>>::backing_planes ()
(gdb) where
#0  0x0000561230bb4f83 in xcb::xproto::<impl xcb::base::Reply<xcb::ffi::xproto::xcb_get_window_attributes_reply_t>>::backing_planes ()
#1  0x0000561230bb2ca3 in xidlehook_core::modules::xcb::Xcb::get_idle ()
#2  0x0000561230b042fd in <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll ()
#3  0x0000561230b1f225 in <tokio::future::poll_fn::PollFn<F> as core::future::future::Future>::poll ()
#4  0x0000561230b0058f in <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll ()
#5  0x0000561230b1b93a in std::thread::local::LocalKey<T>::with ()
#6  0x0000561230b102b3 in tokio::runtime::basic_scheduler::BasicScheduler<P>::block_on ()
#7  0x0000561230b1cb2c in tokio::runtime::Runtime::block_on ()
#8  0x0000561230b25cea in xidlehook::main ()
#9  0x0000561230b1f5c3 in std::sys_common::backtrace::__rust_begin_short_backtrace ()
#10 0x0000561230b1f5dd in std::rt::lang_start::{{closure}} ()
#11 0x0000561230c50521 in core::ops::function::impls::{{impl}}::call_once<(),Fn<()>> (self=..., args=<optimized out>) at /usr/src/rustc-1.49.0/library/core/src/ops/function.rs:259
#12 std::panicking::try::do_call<&Fn<()>,i32> (data=<optimized out>) at library/std/src/panicking.rs:381
#13 std::panicking::try<i32,&Fn<()>> (f=...) at library/std/src/panicking.rs:345
#14 std::panic::catch_unwind<&Fn<()>,i32> (f=...) at library/std/src/panic.rs:396
#15 std::rt::lang_start_internal (main=..., argc=<optimized out>, argv=<optimized out>) at library/std/src/rt.rs:51
#16 0x0000561230b25db2 in main ()