gistfile1.cpp

        static int EIO_AfterDrawMap(eio_req *req) {
          HandleScope scope;
          drawmap_request *drawmap_req =(drawmap_request *)req->data;
          ev_unref(EV_DEFAULT_UC);
          drawmap_req->map->Unref();

          Local<Value> argv[2];
          if (drawmap_req->data != NULL) {
            Buffer * buffer = Buffer::New(drawmap_req->data, drawmap_req->size, FreeImageBuffer, NULL);

            argv[0] = Local<Value>::New(Null());
            argv[1] = Local<Value>::New(buffer->handle_));
          } else {
            errorObj * err = msGetErrorObj();
            Local<Value> _arg_ = External::New(err);

            argv[0] = Local<Value>::New(ErrorObj::constructor_template->GetFunction()->NewInstance(1, &_arg_));
            argv[1] = Local<Value>::New(Null());
          }

          TryCatch try_catch;

          drawmap_req->cb->Call(Context::GetCurrent()->Global(), 2, argv);

          if (try_catch.HasCaught()) {
            FatalException(try_catch);
          }

          drawmap_req->cb.Dispose();
          delete drawmap_req;
          return 0;
        }

moved TryCatch to before if, removed extraneous ) on line 12, get this in error case:

node(17393,0x7fff70132ca0) malloc: *** error for object 0x202020202020307: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap