Steps to reproduce:
1. Open the attached project (case_1201344_ShaderWarmUp.zip)
2. Ensure that the Graphics API is OpenGLCore or OpenGLES3
3. Ensure that "New Material" and "New Material 1" have "Enable GPU Instancing" checked in the Inspector
4. Enter Play Mode

Expected result: Editor continues working as usual
Actual result: Editor crashes

Reproduced in: 2019.3.0b4, 2019.3.0f4, 2020.1.0a18
Not reproducible in: 2017.4.36f1, 2018.4.15f1, 2019.2.17f1, 2019.3.0b3

Note:
- Only occurs when using OpenGLCore or OpenGLES3 Graphics APIs
- 2020.1 is much less prone to crashing as it takes around up to 10 attempts (entering Play Mode) whereas in 2019.3 the crash is reproducible 100% of the time
- The crash produces three seemingly different stack traces, one of which is an explicit segmentation fault
- Adding the shaders used by the instanced materials to a ShaderVariantCollection and calling WarmUp() for it does not reproduce the issue