Cube example crashes when minimizing the window

[YuuriMomo]

Description
When running cube example and minimizing the window on windows the cube example crashes

Repro steps
Ideally, a runnable example we can check out.
https://github.com/gfx-rs/wgpu-rs 7396e92

Expected vs observed behavior
Window should minimize without crashing.

Program crashes when minimizing

Extra materials
Screenshots to help explain your problem.
Validation logs can be attached in case there are warnings and errors.
Zip-compressed API traces and GPU captures can also land here.

Platform
Information about your OS, version of wgpu, your tech stack, etc.
Windows 10 version 2004
GPU: 1050ti
CPU i5-8300H

[kvark]

Let's consider this a dupe of gfx-rs/wgpu-rs#316