Steps for reproduction:
1) Download project `AreaLightCrash` below
2) Open the scene `Skybox`
3) Generate the lighting
4) Observe the crash

Notes:
- Issue became noticeable when new light modes feature for Progressive Lightmapper is merged (introduced in 2017.3.0a5)
- Before 2017.3.0a5, editor didn't crash but baking process used to get stall for awhile but it always managed to finish baking successfully
- Re-authoring normals of the mesh in a DCC package resolves the issue
- Re-calculating the normals in Unity editor and changing `pushoff` parameter of the custom lightmap parameter resolves the issue (no more crash)
- Crash doesn't occur when standard shader is assigned to GameObject called "NightRoom_Skybox"
- Crash doesn't occur when another type of light is used in place of area light
- Crash only occurs when `Lightmap Resolution` is equal or higher than 19
- Crash is not related to `View Prioritization`, issue occurs regardless of this option
- Crash occurs regardless of supersampling
- Issue is not related to directional lightmaps
- Issue is not related to backface tolerance

- Workaround solution is to change the render queue of a transparent shader from 3000 to another value