fix: remove event monitor before destroying window (4-0-x) (#16063)

atom/browser/native_window_mac.mm

@@ -473,7 +473,8 @@ NativeWindowMac::NativeWindowMac(const mate::Dictionary& options,
 }
 
 NativeWindowMac::~NativeWindowMac() {
-  [NSEvent removeMonitor:wheel_event_monitor_];
+  if (wheel_event_monitor_)
+    [NSEvent removeMonitor:wheel_event_monitor_];
 }
 
 void NativeWindowMac::SetContentView(views::View* view) {
@@ -510,6 +511,13 @@ void NativeWindowMac::Close() {
 }
 
 void NativeWindowMac::CloseImmediately() {
+  // Remove event monitor before destroying window, otherwise the monitor may
+  // call its callback after window has been destroyed.
+  if (wheel_event_monitor_) {
+    [NSEvent removeMonitor:wheel_event_monitor_];
+    wheel_event_monitor_ = nil;
+  }
+
   // Retain the child window before closing it. If the last reference to the
   // NSWindow goes away inside -[NSWindow close], then bad stuff can happen.
   // See e.g. http://crbug.com/616701.