The project is already rigged to crash the Shader Compiler upon launch, the following steps are too replicate the crash.

1) Open attached project
2) Open Terrain.shader
3) Go to line 110
4) Switch the commenting so that "outAlbedo = lerp(albedo, parentAlbedo, LODMorphValue).rgb;" would be disabled and "outAlbedo = 0;" would be enabled
5) Save it
6) Open the shader and the material in Inspector - notice all goes okay
7) Disable Instancing on the Material in Inspector
8) Repeat steps 2-5, but reverse what's enabled/disabled when doing step 4
9) Do step 6 - notice that everything is still okay
10) Enable Instancing on the Material

Expected: Nothing happens
Actual: Shader Compiler crashes and the material becomes unusable until shader is fixed

Reproduced in 5.5.0b11, 5.5.1p2, 5.6.0b6 (note, the Instancing flag is not exposed in 5.5 versions, but it is not needed to reproduce the issue on older versions)
Can't test on pre-5.5.0b11 as shader has errors when imported there