Fixed CI issues with Xml comments and some NRT issues

Author: KathleenDollard

src/System.CommandLine.Subsystems/PipelineResult.cs

@@ -5,11 +5,11 @@
 
 namespace System.CommandLine;
 
-public class PipelineResult(ParseResult? parseResult, string rawInput, Pipeline? pipeline, ConsoleHack? consoleHack = null)
+public class PipelineResult(ParseResult parseResult, string rawInput, Pipeline? pipeline, ConsoleHack? consoleHack = null)
 {
     // TODO: Try to build workflow so it is illegal to create this without a ParseResult
     private readonly List<ParseError> errors = [];
-    public ParseResult? ParseResult { get; } = parseResult;
+    public ParseResult ParseResult { get; } = parseResult;
     private ValueProvider valueProvider { get; } = new ValueProvider(parseResult);
     public string RawInput { get; } = rawInput;
 
@@ -26,8 +26,8 @@ public class PipelineResult(ParseResult? parseResult, string rawInput, Pipeline?
     public object? GetValue(CliValueSymbol option)
         => valueProvider.GetValue<object?>(option);
 
-    public CliValueResult GetValueResult(CliValueSymbol dataSymbol)
-     => parseResult.GetValueResult(dataSymbol);
+    public CliValueResult? GetValueResult(CliValueSymbol dataSymbol)
+     => ParseResult.GetValueResult(dataSymbol);
 
 
     public void AddErrors(IEnumerable<ParseError> errors)

src/System.CommandLine/ParseResult.cs

@@ -205,7 +205,7 @@ CommandLineText is null
         /// <summary>
         /// Gets the ValueResult, if any, for the specified option or argument
         /// </summary>
-        /// <param name="option">The option for which to find a result.</param>
+        /// <param name="valueSymbol">The option or argument for which to find a result.</param>
         /// <returns>A result for the specified option, or <see langword="null"/> if it was not entered by the user.</returns>
         public CliValueResult? GetValueResult(CliValueSymbol valueSymbol)
             => GetValueResultInternal(valueSymbol);