Object reference not set to an instance of an object when using url() in mixin

[CodeTrailblazer]

Hi, using the core library in the dotless.1.5.2 nuget package i'm having problems with mixins that use the css 'url()' function.

Having the sample:
`.cssClass
{
background-image:url('image.png');
}

.newCssClass
{
.cssClass;
color:#000;
}
`
and calling the parser's static method

dotless.Core.Less.Parse(sLessCss);
produces a "Object reference not set to an instance of an object" exception.

Stack Trace:
[NullReferenceException: Object reference not set to an instance of an object.]
dotless.Core.Parser.Tree.Url.CloneCore() +57
dotless.Core.Parser.Infrastructure.Nodes.Node.Clone() +22
dotless.Core.Parser.Tree.Rule.CloneCore() +30
dotless.Core.Parser.Infrastructure.Nodes.Node.Clone() +22
dotless.Core.Parser.Infrastructure.Nodes.NodeList1.<CloneCore>b__0(TNode i) +19 System.Linq.WhereSelectListIterator2.MoveNext() +243
System.Collections.Generic.List1..ctor(IEnumerable1 collection) +535
dotless.Core.Parser.Infrastructure.Nodes.NodeList`1.CloneCore() +404
dotless.Core.Parser.Infrastructure.Nodes.Node.Clone() +22
dotless.Core.Parser.Tree.MixinCall.Evaluate(Env env) +1229
dotless.Core.Utils.NodeHelper.ExpandNodes(Env env, NodeList rules) +130
dotless.Core.Parser.Tree.Ruleset.EvaluateRules(Env env) +291
dotless.Core.Parser.Tree.Ruleset.Evaluate(Env env) +253
dotless.Core.Parser.Tree.Ruleset.EvaluateRules(Env env) +686
dotless.Core.Parser.Tree.Root.Evaluate(Env env) +391
dotless.Core.Parser.Tree.Root.AppendCSS(Env env) +92
dotless.Core.Parser.Infrastructure.Output.Append(Node node) +69
dotless.Core.Parser.Infrastructure.Nodes.Node.ToCSS(Env env) +100
dotless.Core.LessEngine.TransformToCss(String source, String fileName) +481
dotless.Core.CacheDecorator.TransformToCss(String source, String fileName) +237
dotless.Core.ParameterDecorator.TransformToCss(String source, String fileName) +664
ASP.default_aspx.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in d:[WebProjects]\FlyableAC\Default.aspx:1331
System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +130
System.Web.UI.Page.Render(HtmlTextWriter writer) +39
System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +149
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5362

Any help is appreciated, thanks.

[rytmis]

The stack trace looks like the Value property of the Url node is null. I'm not quite sure what that implies, so I'll have to debug this a bit at some point. Unfortunately I'm rather busy at the moment.

You can get around the problem by wrapping the URL in a quoted literal:

.cssClass
{
  background-image: ~"url('image.png')";
}

.newCssClass
{
  .cssClass;
  color:#000;
}