Steps to reproduce:

1) Download attached project and open in Unity
2) Switch platform in the Build Settings from Android to PC/Mac/ Linux Standalone
If Editor didn't crash, keep switching the platforms

========== OUTPUTTING STACK TRACE ==================

0x00007FFE4591039E (mono) [c:\buildslave\mono\build\mono\metadata\class.c:7046] mono_class_array_element_size
0x0000000140C9D741 (Unity) scripting_array_new
0x0000000140F0EC39 (Unity) GetUnityAssembliesManaged
0x0000000140F13E69 (Unity) SetAllUnityAssemblies
0x0000000140F11FC1 (Unity) OnBuildTargetChanged
0x00000001413EB4AB (Unity) EditorUserBuildSettings::SetActiveBuildTargetAndGroup
0x0000000140E1EE56 (Unity) PerformDeferredSwitchActiveBuildTargetForEmulation
0x00000001406AF379 (Unity) CallbackArray::Invoke
0x000000014148F666 (Unity) Application::TickTimer
0x00000001416914F1 (Unity) MainMessageLoop
0x00000001416934DE (Unity) WinMain
0x00000001427DC0E7 (Unity) __scrt_common_main_seh

Reproduced with:
2018.1.0a6, 2018.1.0a7

Not reproduced with:
2017.1.2p3, 2017.2.0p4, 2017.3.0f3, 2018.1.0a5

Regression since:
2018.1.0a6

Note: Tested using Windows machine. Reproducible with other platforms too.