thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: ()', src/libcore/result.rs:1009:5
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:59
             at src/libstd/panicking.rs:211
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:227
   4: <std::panicking::begin_panic::PanicPayload<A> as core::panic::BoxMeUp>::get
             at src/libstd/panicking.rs:491
   5: std::panicking::continue_panic_fmt
             at src/libstd/panicking.rs:398
   6: std::panicking::try::do_call
             at src/libstd/panicking.rs:325
   7: core::char::methods::<impl char>::escape_debug
             at src/libcore/panicking.rs:95
   8: <parking_lot::raw_mutex::RawMutex as lock_api::mutex::RawMutex>::unlock
             at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libcore/macros.rs:26
   9: <parking_lot::raw_mutex::RawMutex as lock_api::mutex::RawMutex>::unlock
             at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libcore/result.rs:808
  10: core::alloc::Layout::repeat
             at wgpu-native/src/swap_chain.rs:159
  11: wgpu::TextureCopyView::into_native
             at wgpu-rs/src/lib.rs:673
  12: core::ptr::real_drop_in_place
             at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libcore/ptr.rs:204
  13: cube::framework::run
             at gfx-examples/src/framework.rs:111
  14: cube::main
             at gfx-examples/src/cube.rs:330
  15: std::rt::lang_start::{{closure}}
             at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libstd/rt.rs:74
  16: std::panicking::try::do_call
             at src/libstd/rt.rs:59
             at src/libstd/panicking.rs:310
  17: panic_unwind::dwarf::eh::read_encoded_pointer
             at src/libpanic_unwind/lib.rs:102
  18: <std::panicking::begin_panic::PanicPayload<A> as core::panic::BoxMeUp>::get
             at src/libstd/panicking.rs:289
             at src/libstd/panic.rs:398
             at src/libstd/rt.rs:58
  19: std::rt::lang_start
             at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libstd/rt.rs:74
  20: <cube::Vertex as core::clone::Clone>::clone