fix(coreaudio): UB and silent failure in loopback device creation (#1123)

Author: thewh1teagle

CHANGELOG.md

@@ -43,6 +43,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **ALSA**: Fix rare panics when dropping the stream is interrupted.
 - **ASIO**: Fix enumeration returning only the first device when using `collect`.
 - **ASIO**: Fix device enumeration and stream creation failing when called from spawned threads.
+- **CoreAudio**: Fix undefined behaviour and silent failure in loopback device creation.
 - **Emscripten**: Fix build failure introduced by newer `wasm-bindgen` versions.
 
 ## [0.17.3] - 2026-02-18

src/host/coreaudio/macos/loopback.rs

@@ -103,18 +103,20 @@ impl LoopbackDevice {
 
         let mut tap_obj_id: MaybeUninit<AudioObjectID> = MaybeUninit::uninit();
         let tap_obj_id = unsafe {
-            AudioHardwareCreateProcessTap(Some(tap_desc.as_ref()), tap_obj_id.as_mut_ptr());
+            let status =
+                AudioHardwareCreateProcessTap(Some(tap_desc.as_ref()), tap_obj_id.as_mut_ptr());
+            check_os_status(status)?;
             tap_obj_id.assume_init()
         };
         let tap_uid = unsafe { tap_desc.UUID().UUIDString() };
 
         // 2 - Create aggregate device
         let aggregate_device_properties = create_audio_aggregate_device_properties(tap_uid);
-        let aggregate_device_id: AudioObjectID = 0;
+        let mut aggregate_device_id: AudioObjectID = 0;
         let status = unsafe {
             AudioHardwareCreateAggregateDevice(
                 aggregate_device_properties.as_ref(),
-                NonNull::from(&aggregate_device_id),
+                NonNull::from(&mut aggregate_device_id),
             )
         };
         check_os_status(status)?;