On X11, fix error propagation in EventLoop::new

Fixes #3350.

CHANGELOG.md

@@ -11,6 +11,7 @@ Unreleased` header.
 
 # Unreleased
 
+- On X11, fix `NotSupported` error not propagated when creating event loop.
 - On Wayland, fix resize not issued when scale changes
 - On X11 and Wayland, fix arrow up on keypad reported as `ArrowLeft`.
 - On Windows, macOS, X11, Wayland and Web, implement setting images as cursors. See the `custom_cursors.rs` example.

src/platform_impl/linux/mod.rs

@@ -756,7 +756,7 @@ impl<T: 'static> EventLoop<T> {
             #[cfg(wayland_platform)]
             Backend::Wayland => EventLoop::new_wayland_any_thread().map_err(Into::into),
             #[cfg(x11_platform)]
-            Backend::X => Ok(EventLoop::new_x11_any_thread().unwrap()),
+            Backend::X => EventLoop::new_x11_any_thread().map_err(Into::into),
         }
     }
 
@@ -766,10 +766,10 @@ impl<T: 'static> EventLoop<T> {
     }
 
     #[cfg(x11_platform)]
-    fn new_x11_any_thread() -> Result<EventLoop<T>, XNotSupported> {
+    fn new_x11_any_thread() -> Result<EventLoop<T>, EventLoopError> {
         let xconn = match X11_BACKEND.lock().unwrap().as_ref() {
             Ok(xconn) => xconn.clone(),
-            Err(err) => return Err(err.clone()),
+            Err(_) => return Err(EventLoopError::NotSupported(NotSupportedError::new())),
         };
 
         Ok(EventLoop::X(x11::EventLoop::new(xconn)))