Steps to reproduce:

1) Open Unity and click on "New" button(to create a new project)
2) Select High Definition RP(preview) template
3) Click "Create project" button
It will crash in the assets importing/compilation process

Reproduced with:
2018.3.0a1

Not reproduced with:
2018.2.0b7

Regression since:
2018.3.0a1

Reproduced using Windows machine:
CPU: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
GPU: NVIDIA GeForce GTX 1050 Ti with 4GB VRAM
Memory: 32GB

Did not reproduced this crash using macOS machine:
MacBook Pro (15-inch, 2017)
Memory: 16GB
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Fixed in: 2018.3.0a4