Editor freezes on clicking on start test and after some time it throws following errors. I feel the errors are related to custom editor script and test case need to be improved.

Steps to Repro:
1. Open attached project
2. Video Tests > Config Video Importer Tests
3. Select directory where video clips are located
4. Check Video Importer property > select few video importer options
5. Run Test Importer

Actual Result:
Observe that editor freezes and throws errors after sometime

Occurring with:
2018.1.0b11, 2018.1.0b6, 2018.1.0b1, 2017.3.1p4

Environment:
Windows 10 & Mac OSX 10.13

Stack Trace:
Error1:
NullReferenceException: Object reference not set to an instance of an object
VideoImporterTestConfig.HandleException (System.String condition, System.String stackTrace, LogType type) (at Assets/Editor/VideoImporterTestConfig.cs:90)
UnityEngine.Application.CallLogCallback (System.String logString, System.String stackTrace, LogType type, Boolean invokedOnMainThread) (at C:/buildslave/unity/build/artifacts/generated/bindings_old/common/Core/ApplicationBindings.gen.cs:577)

Error 2:
ArgumentOutOfRangeException: StartIndex can not be less than zero
Parameter name: startIndex
System.String.Remove (Int32 startIndex) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/String.cs:1480)
VideoImporterTestConfig.OnGUI () (at Assets/Editor/VideoImporterTestConfig.cs:244)
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 C:/buildslave/unity/build/Editor/Mono/HostView.cs:291)
UnityEditor.HostView.Invoke (System.String methodName) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:284)
UnityEditor.HostView.InvokeOnGUI (Rect onGUIPosition) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:251)