Unity crashes on play after updating

The game worked perfectly fine in 2018.2.4. I updated to 2018.2.6 (and now 2018.2.7), and now my game is broken.

The main menu works fine, and I run the gameplay scene if it's only a canvas and camera. Hell, as far as I could tell It'll work with just about anything so long as its all alone.

For example, my player object alone - No problem.
Pooling system alone - All good
Player + pool - Crash.

This makes absolutely no sense. It all works fine. In fact, even if I just turn off the player object and the pooling system it still crashes. It's obviously not the individual objects that are causing this issue, but rather everything put together.

When I looked in the editor log, it said that watchdog closed unity. As far as I know, that means there was some kind of infinite loop of some sort, or the engine froze? Except there's no infinite loops in my code. A lot of my exceptions (The ones that could do any real damage, anyway) are handles by try/catch blocks as well.

So then I thought "Maybe the object pool is freezing the engine while spawning objects"
Nope. The pooling makes no difference. Still freezes.

I honestly have no idea what's going on. It worked perfectly fine before. We've put 3 months of work into this project, and were supposed to launch this month. Now I'm getting the feeling that we might not be able to.

So what the hell happened, and how can I fix it?

 

I've found the issue. Enabling or disabling game objects causes unity to freeze, and crash. I found this out by running a scene with no active objects, and manually activating an object.

The object had no dependencies, loops, or anything else. It was essentially a collider with ontriggerenter2D.