Make sure the MTRDevice lock is held when we touch _weakDelegate. (pr…

…oject-chip#31109)

src/darwin/Framework/CHIP/MTRDevice.mm

@@ -327,7 +327,11 @@ - (void)nodeMayBeAdvertisingOperational
 // Return YES if there's a valid delegate AND subscription is expected to report value
 - (BOOL)_subscriptionAbleToReport
 {
-    return (_weakDelegate.strongObject) && (_state == MTRDeviceStateReachable);
+    os_unfair_lock_lock(&self->_lock);
+    id<MTRDeviceDelegate> delegate = _weakDelegate.strongObject;
+    auto state = _state;
+    os_unfair_lock_unlock(&self->_lock);
+    return (delegate != nil) && (state == MTRDeviceStateReachable);
 }
 
 // assume lock is held
@@ -634,6 +638,8 @@ - (void)_handleEventReport:(NSArray<NSDictionary<NSString *, id> *> *)eventRepor
 // assume lock is held
 - (void)_setupSubscription
 {
+    os_unfair_lock_assert_owner(&self->_lock);
+
 #ifdef DEBUG
     id delegate = _weakDelegate.strongObject;
     Optional<System::Clock::Seconds32> maxIntervalOverride;
@@ -645,8 +651,6 @@ - (void)_setupSubscription
     }
 #endif
 
-    os_unfair_lock_assert_owner(&self->_lock);
-
     // for now just subscribe once
     if (_subscriptionActive) {
         return;
@@ -1088,7 +1092,9 @@ - (void)writeAttributeWithEndpointID:(NSNumber *)endpointID
 
     BOOL useValueAsExpectedValue = YES;
 #ifdef DEBUG
+    os_unfair_lock_lock(&self->_lock);
     id delegate = _weakDelegate.strongObject;
+    os_unfair_lock_unlock(&self->_lock);
     if ([delegate respondsToSelector:@selector(unitTestShouldSkipExpectedValuesForWrite:)]) {
         useValueAsExpectedValue = ![delegate unitTestShouldSkipExpectedValuesForWrite:self];
     }