Merge pull request #11099 from electron/fix-emit-call-crash

Fix crash when emitting unhandled error on native EventEmitter

atom/common/api/event_emitter_caller.cc

@@ -20,8 +20,18 @@ v8::Local<v8::Value> CallMethodWithArgs(v8::Isolate* isolate,
                                    v8::MicrotasksScope::kRunMicrotasks);
   // Use node::MakeCallback to call the callback, and it will also run pending
   // tasks in Node.js.
-  return node::MakeCallback(isolate, obj, method, args->size(), &args->front(),
-                            {0, 0}).ToLocalChecked();
+  v8::MaybeLocal<v8::Value> ret = node::MakeCallback(isolate, obj, method,
+                                                     args->size(),
+                                                     &args->front(), {0, 0});
+  // If the JS function throws an exception (doesn't return a value) the result
+  // of MakeCallback will be empty and therefore ToLocal will be false, in this
+  // case we need to return "false" as that indicates that the event emitter did
+  // not handle the event
+  v8::Local<v8::Value> localRet;
+  if (ret.ToLocal(&localRet)) {
+    return localRet;
+  }
+  return v8::Boolean::New(isolate, false);
 }
 
 }  // namespace internal