Ignore fired timer if the object wrapper is no longer alive

gin/modules/timer.cc

Index: gin/modules/timer.cc
diff --git a/gin/modules/timer.cc b/gin/modules/timer.cc
index 9e5a26c8ea9ea88d7033bf38c88007951d43c3aa..e1deeaad8f5698c5f1861d810d2030ae6f11b9c6 100644
--- a/gin/modules/timer.cc
+++ b/gin/modules/timer.cc
@@ -67,9 +67,14 @@ void Timer::OnTimerFired() {
 
   Runner::Scope scope(runner_.get());
   v8::Isolate* isolate = runner_->GetContextHolder()->isolate();
+
+  v8::Local<v8::Object> wrapper;
+  if (!GetWrapper(isolate).ToLocal(&wrapper)) {
+    return;
+  }
+
   v8::Local<v8::Function> function = v8::Local<v8::Function>::Cast(
-      GetWrapper(isolate)
-          .ToLocalChecked()
+      wrapper
           ->GetPrivate(runner_->GetContextHolder()->context(),
                        GetHiddenPropertyName(isolate))
           .ToLocalChecked());