[SOLVED?] Server Tick Loop Error

I am encountering an odd and unique issue I haven't experienced before. There is no new dimension or anything of that sort, only new mobs, items, systems, etc - and its with the bosses in particular.

What is so strange is that after experiencing the crash once, I don't experience it again until my player dies again, but obviously the most crucial problem is that it crashes in the first place.

Here are some of the crash report details:

https://pastebin.com/4T9EVZqc

I consulted someone and they pointed out the following issue in the TribulationMod.java file (my mod is called Tribulation):

  @SubscribeEvent 
    public void tick(TickEvent.ServerTickEvent event) { 
        if (event.phase == TickEvent.Phase.END) { 
            List<AbstractMap.SimpleEntry<Runnable, Integer>> actions = new ArrayList<>(); 
            workQueue.forEach(work -> { 
                work.setValue(work.getValue() - 1); 
                if (work.getValue() == 0) 
                    actions.add(work); 
            });

apparently this is problematic because there is no null check, or something like that. when I try to implement it myself, MCreator automatically overwrites it anyway so no matter what I do the problem remains. Never experienced it before now - is it something in the new code/versions? Am I using too many server side "wait for X ticks" and so on? I'm really intent on getting this issue fixed because its quite critical and I only noticed it recently. 

Thank you for your attention, I hope this can get resolved soon.