Apply suggestion from @JanProvaznik

AR-May · JanProvaznik · web-flow · commit c4e386116e30 · 2026-02-12T18:12:34.000+01:00
Co-authored-by: Jan Provazník &lt;janpro@janpro.dev&gt;
diff --git a/src/Tasks/XmlPeek.cs b/src/Tasks/XmlPeek.cs
@@ -227,7 +227,7 @@ private sealed class XmlInput
             /// <summary>
             /// Contains the raw Xml content when in Xml mode.
             /// </summary>
-            private readonly string _xmlContent;
+            private readonly string? _xmlContent;
 
             /// <summary>
             /// FileStream used to read XML.
