NullReferenceException if adjustRelativePaths="adjustRelativePaths"

[MrStepson]

Version 2.6.13 (VS 2013 SP5) raises NullReferenceException on bungling. I have quite simple config:

<?xml version="1.0" encoding="utf-8"?>

true true true /Content/bootstrap/bootstrap.css

Full exception stack:

04.08.2015 9:06:35: System.NullReferenceException: Object reference not set to an instance of an object. at MadsKristensen.EditorExtensions.FileHelpers.RelativePath(String absolutePath, String relativeTo) at MadsKristensen.EditorExtensions.Helpers.CssUrlNormalizer.FixPath(String url) at MadsKristensen.EditorExtensions.Helpers.CssUrlNormalizer.Visit(ParseItem parseItem) at Microsoft.CSS.Core.ComplexItem.Accept(ICssSimpleTreeVisitor visitor) at Microsoft.CSS.Core.ComplexItem.Accept(ICssSimpleTreeVisitor visitor) at Microsoft.CSS.Core.ComplexItem.Accept(ICssSimpleTreeVisitor visitor) at Microsoft.CSS.Core.ComplexItem.Accept(ICssSimpleTreeVisitor visitor) at Microsoft.CSS.Core.ComplexItem.Accept(ICssSimpleTreeVisitor visitor) at MadsKristensen.EditorExtensions.Helpers.CssUrlNormalizer.NormalizeUrls(BlockItem tree, String targetFile, String oldBasePath) at MadsKristensen.EditorExtensions.BundleGenerator.d10.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MadsKristensen.EditorExtensions.BundleGenerator.d0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MadsKristensen.EditorExtensions.BundleFilesMenu.d2d.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MadsKristensen.EditorExtensions.BundleFilesMenu.d22.MoveNext() 04.08.2015 9:06:35: Error generating the bundle. See output window for details

If change adjustRelativePaths to "false", all works as expected.