I've been said it should be fixed in

2018.2.11f1

the notification email also said something that's been removed from the original post.
I'm posting it here just in case:

Source: https://forum.unity.com/threads/hard-crash-while-light-baking-tetrahedralize-probes-step.410243/#post-3762637
"
It works, even in 2018.2

To make it work, just call it from inside a coroutine, like this:

IEnumerator Tetrah(){
Vector3[] outVerts;
int[] vertIndices_ofTetras;

_verts = new List<Vector3>(){ Vector3.forward, Vector3.back, Vector3.up, Vector3.right };

UnityEditor.Lightmapping.Tetrahedralize(_verts.ToArray(), out vertIndices_ofTetras, out outVerts);
yield return null;
}

"

It works even in 2018.2
To avoid a crash, you need to call it from inside a coroutine.
Have a look here https://forum.unity.com/threads/hard-crash-while-light-baking-tetrahedralize-probes-step.410243/#post-3762637

https://fogbugz.unity3d.com/default.asp?1063168_g9ac557aubdabjqp

This is verified NOT FIXED in 2018.2.4f1

May I ask if you're using some equivalent API instead of Tetrahedralize?
Is Lightmapping.Tetrahedralize still going to be the most efficient implementation of the function it provides, in next Unity Releases, or is it going to be marked as deprecated?