1. Open newly attached project (or fix the originally attached one by following steps in "To fix project steps")
2. Choose MultiScene Editing Tools/Bake All NavMesh Scenes menu item
Expected result: Scenes get baked
Actual result: In addition to that, the errors are also thrown (there is no visible misbehaviour, just the errors)

Note: It works fine when you use indexes instead of names

To fix project steps:
1. Open BakeAllScenes script
2. In line 11 delete the two instances of "Assets/", so that the line reads:
string[] sceneNames = { "Scene1.unity", "Scene2.unity"};