Reproduction steps:
1. Open the attached project.
2. Click on the "Project" tab.
3. Editor crashes.

To fix the project:
- Open it with pre 5.5.0b4 Unity version (e.g. 5.5.0b3).
or
- Delete library.

To brake the project:
1. Open it with 5.6.0a3
2. Select "Console" tab.
3. Open it with 5.6.0a2
4. Open it with 5.6.0a3.
5. Select "Project" tab.

Reproduced in: 5.5.0b4, 5.5.0f1, 5.6.0a3.
Not reproducible in: 5.5.0b3.

Regression introduced in:
5.5.0b4 (It is possible that 5.5.0b3 just fixes the project)
or
5.6.0a3 (Version that breaks the project)

May be related:
Case 849847

Stack trace:
#0 0x000001012ed940 in TextureForClass(Unity::Type const*)
#1 0x000001012e4e58 in GetCachedAssetDatabaseIcon(UnityGUID const&, Asset const&, LibraryRepresentation const&)
#2 0x000001012e4c10 in GetCachedAssetDatabaseIcon(core::basic_string<char, core::StringStorageDefault<char> > const&)
#3 0x0000010220dc70 in AssetDatabase_CUSTOM_GetCachedIcon(MonoString*)
#4 0x0000011d7df0d2 in (wrapper managed-to-native) UnityEditor.AssetDatabase:GetCachedIcon (string) + 0x92 (0x11d7df040 0x11d7df101) [0x116f43660 - Unity Child Domain]
#5 0x0000011d7df671 in UnityEditor.FilteredHierarchy/FilterResult:get_icon () + 0x191 (0x11d7df4e0 0x11d7df894) [0x116f43660 - Unity Child Domain]
#6 0x0000011c37b473 in UnityEditor.ObjectListArea/LocalGroup:DrawItem (UnityEngine.Rect,UnityEditor.FilteredHierarchy/FilterResult,UnityEditor.BuiltinResource,bool) + 0x31d3 (0x11c3782a0 0x11c37e894) [0x116f43660 - Unity Child Domain]
#7 0x0000011c3767f8 in UnityEditor.ObjectListArea/LocalGroup:DrawInternal (int,int,single) + 0xac8 (0x11c375d30 0x11c376c80) [0x116f43660 - Unity Child Domain]
#8 0x0000011c374b8f in UnityEditor.ObjectListArea/Group:Draw (single,UnityEngine.Vector2) + 0x7bf (0x11c3743d0 0x11c374c7f) [0x116f43660 - Unity Child Domain]
#9 0x0000011c37220f in UnityEditor.ObjectListArea:HandleListArea () + 0xfbf (0x11c371250 0x11c372c84) [0x116f43660 - Unity Child Domain]
#10 0x0000011c36e61a in UnityEditor.ObjectListArea:OnGUI (UnityEngine.Rect,int) + 0x8ca (0x11c36dd50 0x11c36e6b4) [0x116f43660 - Unity Child Domain]
...