NullReferenceException is thrown when the "var" CSS function is used in the HTML on HtmlFormatProvider Import method call.
The exception occurs only for CSS properties processed by RadRichTextBox. For example: "vertical-align", "font-family", "font-weight", "text-decoration-underline", etc.
The following HTML produces such error:
<span style="vertical-align: var(--my-variable);">
</span>
If the span tag doesn't have any content, the error doesn't occur.
The exception stacktrace is:
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.FillSpanProperties(SpanProperties spanProps, EvaluateProperty evalFunction, IEnumerable`1 disregarderdDefaultStyleBagPropertiesCollection)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.CreateSpanFromTextNode(INode childNode, Paragraph paragraph, IEnumerable`1 disregarderdDefaultStyleBagPropertiesCollection)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessContentNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessHyperlinkNode(INode node, Action innerAction)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessAnnotationsForNode(INode node, Action innerAction)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.Import(Stream input)
To work this around, avoid using the "var" function in the CSS.
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