x11: Improve error handling (#32913)

Continuing this work from a while back in #21079, now greatly aided by
agent + sonnet 4. With this change, there are now only a few spots that
explicitly panic, though errors during initialization will panic.

Motivation was this recent user panic in `handle_event`, figured fixing
all this use of unwrap was a great use of the agent.

> called `Result::unwrap()` on an `Err` value: X11 GetProperty for
_NET_WM_STATE failed.

Release Notes:

- N/A

crates/gpui/src/platform.rs

@@ -93,6 +93,9 @@ pub(crate) fn current_platform(headless: bool) -> Rc<dyn Platform> {
 
 #[cfg(any(target_os = "linux", target_os = "freebsd"))]
 pub(crate) fn current_platform(headless: bool) -> Rc<dyn Platform> {
+    #[cfg(feature = "x11")]
+    use anyhow::Context as _;
+
     if headless {
         return Rc::new(HeadlessClient::new());
     }
@@ -102,7 +105,11 @@ pub(crate) fn current_platform(headless: bool) -> Rc<dyn Platform> {
         "Wayland" => Rc::new(WaylandClient::new()),
 
         #[cfg(feature = "x11")]
-        "X11" => Rc::new(X11Client::new()),
+        "X11" => Rc::new(
+            X11Client::new()
+                .context("Failed to initialize X11 client.")
+                .unwrap(),
+        ),
 
         "Headless" => Rc::new(HeadlessClient::new()),
         _ => unreachable!(),