fix: crash on macOS

The crash log:
'called `Option::unwrap()` on a `None` value'. (File: src/renderer/renderer.rs; Line: 109, Column: 18)

It is mainly because call DX12 on all platform.
After change to conditional choose GPU, macOS require get METAL in UI
thread

KNOWN ISSUE: the window is transparent in macOS, only the titlebar is
presented

src/renderer/renderer.rs

@@ -83,8 +83,8 @@ impl WGpuRenderer {
             let size = window.inner_size();
 
             // The instance is a handle to our GPU
-            // Backends::all => Vulkan + Metal + DX12 + Browser WebGPU
-            let instance = Instance::new(Backends::DX12);
+            // Backends::all() => Vulkan + Metal + DX12 + Browser WebGPU
+            let instance = Instance::new(Backends::all());
 
             // # Safety
             // The surface needs to live as long as the window that created it.

src/window/mod.rs

@@ -405,6 +405,11 @@ pub fn create_window() {
 
     let (txtemp, rx) = mpsc::channel::<Event<UserEvent>>();
     let mut tx = Some(txtemp);
+
+    // the Instance::new(Backends::all()); in macos requires running in main thread
+    // otherwise it will throw error of running in non-UI thread
+    let wgpu_renderer = WGpuRenderer::new(&window);
+
     let mut render_thread_handle = Some(thread::spawn(move || {
         let initial_size = window.inner_size();
 
@@ -448,8 +453,6 @@ pub fn create_window() {
             renderer.grid_renderer.font_dimensions,
         );
 
-        let wgpu_renderer = WGpuRenderer::new(&window);
-
         let mut window_wrapper = WinitWindowWrapper {
             wgpu_renderer,
             window,