To reproduce:

1. Download and open attached "Learn Roughlike2D.zip" project.
2. Download and install Visual Studio Code if you do not have it.
3. Install Unity Debugger Extension version 1.2.1 for Visual Studio Code.
4. Open your Unity project folder in the VS Code.
5. Navigate to Assets->Scripts and open Enemy.cs trough VS Code.
6. Set a breakpoint on line 45 "(this.animator.SetTrigger("attack");"
7. Debug your code with Unity attached.
8. Return to Unity editor and enter Play mode.
9. Move player using arrow keys so he would collide with the enemy.
10. When the breakpoint hits, move your mouse cursor on "animator" word in line 45 "this.animator.SetTrigger("attack");" to get know what value it has.

Expected result: VS Code shows what value this line had and after getting back to Unity it is possible to continue working.
Actual result: VS code shows the value of animator and Unity crashes afterwards.

Reproduced with: 2017.3.0b1, 2017.2.0f1, 2017.1.1p2, 5.6.3p3.

Notes: After hovering on "animator" keyword the crash might occur in time interval from 1 to 5 seconds. Crash appears only when trying to debug lines with animator property. Also happens when debugging with MonoDevelop.

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Response:
This looks like a bug in in the old Mono run time library code. I wasn't able to reproduce this using the new Mono scripting run time library. As we are moving towards phasing out the old run time and replacing with the new one, we are unable to spend resources on fixing this. Please use the new scripting run time if this bug interferes with your work.