IndexOutOfRangeException is thrown on console when user selects "Edit Layers" or "Tags and Layers".

Steps to reproduce:
1. Create a new project.
2. Select Layer drop down menu in the Inspector.
3. Select "Edit Layers..."
OR
2. Edit > Project Settings > Tags and Layers

Observe IndexOutOfRangeException thrown on console.

Reproducible on:
Unity 2018.2.0b4, 2018.2.0b2

Works fine on:
Unity 2018.2.0b1, 2018.2.0a8, 2018.1.0f2, 2017.3.0f3

Environment:
Only on Mac 10.12 and Mac 10.13

Stack Trace:
IndexOutOfRangeException: Array index is out of range.
UnityEditor.ProjectBrowser.RefreshSplittedSelectedPath () (at /Users/builduser/buildslave/unity/build/Editor/Mono/ProjectBrowser.cs:1764)
UnityEditor.ProjectBrowser.GetBottomBarHeight () (at /Users/builduser/buildslave/unity/build/Editor/Mono/ProjectBrowser.cs:1782)
UnityEditor.ProjectBrowser.CalculateRects () (at /Users/builduser/buildslave/unity/build/Editor/Mono/ProjectBrowser.cs:1798)
UnityEditor.ProjectBrowser.OnGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/ProjectBrowser.cs:1864)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:295)
UnityEditor.HostView.Invoke (System.String methodName) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:288)
UnityEditor.HostView.InvokeOnGUI (Rect onGUIPosition) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:254)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

ArgumentException: Getting control 2's position in a group with only 2 controls when doing Repaint
Aborting
UnityEngine.GUILayoutGroup.GetNext () (at /Users/builduser/buildslave/unity/build/Modules/IMGUI/LayoutGroup.cs:117)
UnityEngine.GUILayoutUtility.BeginLayoutArea (UnityEngine.GUIStyle style, System.Type layoutType) (at /Users/builduser/buildslave/unity/build/Modules/IMGUI/GUILayoutUtility.cs:361)
UnityEngine.GUILayout.BeginArea (Rect screenRect, UnityEngine.GUIContent content, UnityEngine.GUIStyle style) (at /Users/builduser/buildslave/unity/build/Modules/IMGUI/GUILayout.cs:287)
UnityEngine.GUILayout.BeginArea (Rect screenRect) (at /Users/builduser/buildslave/unity/build/Modules/IMGUI/GUILayout.cs:275)
UnityEditor.ProjectBrowser.TopToolbar () (at /Users/builduser/buildslave/unity/build/Editor/Mono/ProjectBrowser.cs:2056)
UnityEditor.ProjectBrowser.OnGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/ProjectBrowser.cs:1883)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:295)
UnityEditor.HostView.Invoke (System.String methodName) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:288)