Program: 27558
Project: 27558
Buggy source:
@Override public boolean post(Event event,boolean forced){
  org.spongepowered.api.event.Event spongeEvent=null;
  try (final CauseStackManager.CauseStackFrame frame=Sponge.getCauseStackManager().pushCauseFrame()){
    if (!forced) {
      if (!isEventAllowed(event)) {
        return false;
      }
      spongeEvent=SpongeForgeEventFactory.createSpongeEvent(event);
    }
    IEventListener[] listeners=event.getListenerList().getListeners(this.busID);
    if (!forced && (event instanceof org.spongepowered.api.event.Event || spongeEvent != null) && !Sponge.getGame().getPlatform().getExecutionType().isClient()) {
      boolean cancelled=((SpongeModEventManager)SpongeImpl.getGame().getEventManager()).post(spongeEvent,event,listeners);
      if (!cancelled) {
        SpongeForgeEventFactory.onForgePost(event);
      }
      return cancelled;
    }
    listeners=event.getListenerList().getListeners(this.busID);
    int index=0;
    IMixinASMEventHandler modListener=null;
    try {
      for (; index < listeners.length; index++) {
        final IEventListener listener=listeners[index];
        if (listener instanceof IMixinASMEventHandler) {
          modListener=(IMixinASMEventHandler)listener;
          modListener.getTimingsHandler().startTimingIfSync();
          SpongeForgeEventHooks.preEventPhaseCheck(listener,event);
          listener.invoke(event);
          SpongeForgeEventHooks.postEventPhaseCheck(listener,event);
          modListener.getTimingsHandler().stopTimingIfSync();
        }
 else {
          listener.invoke(event);
        }
      }
    }
 catch (    Throwable throwable) {
      if (modListener != null) {
        modListener.getTimingsHandler().stopTimingIfSync();
      }
      this.exceptionHandler.handleException((EventBus)(Object)this,event,listeners,index,throwable);
      throw new RuntimeException(throwable);
    }
  }
   return (event.isCancelable() ? event.isCanceled() : false);
}

Fixed version (ground truth):
@Override public boolean post(Event event,boolean forced){
  org.spongepowered.api.event.Event spongeEvent=null;
  if (!isSpongeSetUp) {
    try {
      Sponge.getCauseStackManager();
    }
 catch (    Exception e) {
      return false;
    }
  }
  isSpongeSetUp=true;
  final boolean isMainThread=Sponge.isServerAvailable() && Sponge.getServer().isMainThread();
  try (final CauseStackManager.CauseStackFrame frame=isMainThread ? Sponge.getCauseStackManager().pushCauseFrame() : null){
    if (!forced) {
      if (!isEventAllowed(event)) {
        return false;
      }
      spongeEvent=SpongeForgeEventFactory.createSpongeEvent(event);
    }
    IEventListener[] listeners=event.getListenerList().getListeners(this.busID);
    if (!forced && (event instanceof org.spongepowered.api.event.Event || spongeEvent != null) && !Sponge.getGame().getPlatform().getExecutionType().isClient()) {
      boolean cancelled=((SpongeModEventManager)SpongeImpl.getGame().getEventManager()).post(spongeEvent,event,listeners);
      if (!cancelled) {
        SpongeForgeEventFactory.onForgePost(event);
      }
      return cancelled;
    }
    listeners=event.getListenerList().getListeners(this.busID);
    int index=0;
    IMixinASMEventHandler modListener=null;
    try {
      for (; index < listeners.length; index++) {
        final IEventListener listener=listeners[index];
        if (listener instanceof IMixinASMEventHandler) {
          modListener=(IMixinASMEventHandler)listener;
          modListener.getTimingsHandler().startTimingIfSync();
          SpongeForgeEventHooks.preEventPhaseCheck(listener,event);
          listener.invoke(event);
          SpongeForgeEventHooks.postEventPhaseCheck(listener,event);
          modListener.getTimingsHandler().stopTimingIfSync();
        }
 else {
          listener.invoke(event);
        }
      }
    }
 catch (    Throwable throwable) {
      if (modListener != null) {
        modListener.getTimingsHandler().stopTimingIfSync();
      }
      this.exceptionHandler.handleException((EventBus)(Object)this,event,listeners,index,throwable);
      throw new RuntimeException(throwable);
    }
    return (event.isCancelable() ? event.isCanceled() : false);
  }
 }