Try to prevent leaks.

native/Avalonia.Native/src/OSX/automation.mm

@@ -30,6 +30,7 @@ public:
     
     virtual void Dispose() override
     {
+        _owner = nil;
     }
     
     virtual void ChildrenChanged () override
@@ -48,7 +49,7 @@ public:
     }
     
 private:
-    AvnAccessibilityElement* _owner;
+    __strong AvnAccessibilityElement* _owner;
 };
 
 @implementation AvnAccessibilityElement
@@ -90,6 +91,13 @@ private:
     return self;
 }
 
+- (void)dealloc
+{
+    if (_node)
+        delete _node;
+    _node = nullptr;
+}
+
 - (NSString *)description
 {
     return [NSString stringWithFormat:@"%@ '%@' (%p)",