How to reproduce:
1. Open the user-submitted project ("AssetBundleNameBug.zip")
2. Click "Tools" -> "Define Asset Bundle Name With Folder Name"
3. Observe the console errors

Expected result: The Asset bundle names are correctly assigned
Actual result: AssetImporter.assetBundleName fails in some instances

Reproduced in: 2019.1.0a5, 2018.3.0b6, 2018.2.12f1, 2018.2.0a6
Not reproducible in: 2018.2.0a3, 2018.1.9f2, 2017.4.13f1
Couldn't test with: 2018.2.0b2; 2018.2.0a5; 2018.2.0a4 (Project crashes on launch)

Note: "Define Asset Bundle Name With Value Test To Children" method, works for some assets but not for all