Fix async. PlayerStatisticIncrementEvent error by forcing event to run sync. - #2117

This simply won't work as you are expecting.
Inject works by creating an instance of CallbackInfo and pass it into the injector. When the injector returns, the method will check if callback info is cancelled. If it's not it will proceed.
In this case, callback info is submitted to the main thread and wait for processing and cancellation. Meanwhile the injector has already returned and the method checks CallbackInfo and discover it's not cancelled, so the statistics increment will proceed.
You can notice that the cancellation of the event does not work anymore. A good fix might be a main thread check before firing the event. If it's not on the server thread, submit it to the server thread but do not process cancellation. If it's on the server thread, fire synchronously and process cancellation if needed. Doing like this makes the event cancellation useless even on the server thread, which breaks all plugins using this event.