Steps to reproduce:
1. Open QA-supplied project ("UnityReproduce1099646.zip")
2. Open scene "SampleScene"
3. In the Hierarchy window, select "Reproduce"
4. In the Inspector window, press the "Reproduce" button
5. Press 'Undo'

Expected: no crashing
Actual: crashing

Reproduced in: 2018.3.0a6, 2018.3.0b1, 2018.3.0f1, 2019.1.0a11
Not reproduced in: 2018.4.16f1*, 2018.1.9f2*, 2018.2.19f1*, 2018.3.0a5*

Note:
*could not reproduce due to this error:
`UnityEditor.PrefabUtility' does not contain a definition for `SaveAsPrefabAsset'

Full stack trace:
0x000000014010C976 (Unity) Object::GetInstanceID
0x0000000140E0FA20 (Unity) SavePrefab
0x0000000140E71C8B (Unity) UndoManager::Apply
0x0000000140E73F8B (Unity) UndoManager::Undo
0x0000000140DAB9C0 (Unity) EditMenu::Execute
0x000000014126FF07 (Unity) MenuController::ExecuteMenuItem
0x00000001414648C8 (Unity) ProcessMainWindowMessages
0x000000014143F68E (Unity) ContainerWindow::ContainerWndProc
0x00007FFBB2266D41 (USER32) CallWindowProcW
0x00007FFBB2266713 (USER32) DispatchMessageW
0x0000000141464266 (Unity) MainMessageLoop
0x000000014146633E (Unity) WinMain
0x000000014245E80A (Unity) __scrt_common_main_seh
0x00007FFBB1DE3034 (KERNEL32) BaseThreadInitThunk
0x00007FFBB30B1471 (ntdll) RtlUserThreadStart