Fix two manual let-else

src/niri.rs

@@ -1536,13 +1536,10 @@ impl State {
 
                 debug!(session_id, "StartCast");
 
-                let gbm = match self.backend.gbm_device() {
+                let Some(gbm) = self.backend.gbm_device() else {
-                    Some(gbm) => gbm,
-                    None => {
                     warn!("error starting screencast: no GBM device available");
                     self.niri.stop_cast(session_id);
                     return;
-                    }
                 };
 
                 let pw = if let Some(pw) = &self.niri.pipewire {

src/pw_utils.rs

@@ -844,12 +844,9 @@ impl Cast {
             return false;
         }
 
-        let mut buffer = match self.stream.dequeue_buffer() {
+        let Some(mut buffer) = self.stream.dequeue_buffer() else {
-            Some(buffer) => buffer,
-            None => {
             warn!("no available buffer in pw stream, skipping frame");
             return false;
-            }
         };
 
         let fd = buffer.datas_mut()[0].as_raw().fd;