[node] don't dispose parent module in NodeLog destructor

platform/node/src/node_log.cpp

@@ -52,7 +52,6 @@ NodeLogObserver::NodeLogObserver(v8::Local<v8::Object> target)
 
 NodeLogObserver::~NodeLogObserver() {
     queue->stop();
-    module.Reset();
 }
 
 bool NodeLogObserver::onRecord(mbgl::EventSeverity severity, mbgl::Event event, int64_t code, const std::string &text) {

platform/node/src/node_mapbox_gl_native.cpp

@@ -77,7 +77,7 @@ void RegisterModule(v8::Local<v8::Object> target, v8::Local<v8::Object> module)
         Nan::Get(EventEmitter, Nan::New("prototype").ToLocalChecked()).ToLocalChecked());
     Nan::CallAsFunction(EventEmitter, target, 0, nullptr);
 
-    mbgl::Log::setObserver(std::make_unique<node_mbgl::NodeLogObserver>(target->ToObject()));
+    mbgl::Log::setObserver(std::make_unique<node_mbgl::NodeLogObserver>(target));
 }
 
 NODE_MODULE(mapbox_gl_native, RegisterModule)

platform/node/test/js/require.js

@@ -0,0 +1 @@
+var mbgl = require('../../../../lib/mapbox-gl-native');