How to reproduce:
1. Download the user's attached project (Network Test.zip)
2. Extract the project and launch it

Expected results: Unity does not crash
Actual results: Unity crashes instantly

Reproducible with: 2018.2.3f1, 2018.3.0a7
Not reproducible with: 2017.1.5f1, 2017.2.3p3, 2017.4.9f1, 2018.1.9f1
Regression first introduced in: 2018.2.0a3

Note: To look inside the project without crashing, open it in 2018.1.9f1 or earlier versions and load the first scene.

Stack trace:
0x00000001411BE264 (Unity) GetLightingDataAssetFromScene
0x00000001411BE29C (Unity) LightingDataAsset::GetLightingDataAssetStableID
0x000000014117C73B (Unity) WriteLightingDataAssetJob::Prepare
0x0000000141164C19 (Unity) IssueWriteLightingDataAssetJob
0x000000014116532A (Unity) LightingDataAssetManager::PostUpdate
0x0000000141166DAE (Unity) GISceneManager::Update
0x0000000141160E05 (Unity) `GISceneManager::GISceneManager'::`2'::tickGIInEditorRegistrator::Forward
<...>

Workaround:
- For older versions, a possible workaround would be to delete the Library folder and rebuild it by launching the project again - the project will open a new Scene, and you can continue developing from there. Make sure to create a back-up of your project before trying this!