Fix duplicate errors appended

src/System.CommandLine.Tests/ParserTests.cs

@@ -4,13 +4,11 @@
 using System.Collections.Generic;
 using System.CommandLine.Parsing;
 using System.CommandLine.Tests.Utility;
-using System.IO;
 using FluentAssertions;
 using FluentAssertions.Equivalency;
 using System.Linq;
 using FluentAssertions.Common;
 using Xunit;
-using Xunit.Abstractions;
 
 namespace System.CommandLine.Tests
 {
@@ -19,10 +17,10 @@ public partial class ParserTests
         // TODO: Update testing strategy if we use Location in equality. Some will break
         private readonly Location dummyLocation = new("", Location.Internal, -1, null);
 
-        private T GetValue<T>(ParseResult parseResult, CliOption<T> option)
+        private static T GetValue<T>(ParseResult parseResult, CliOption<T> option)
             => parseResult.GetValue(option);
 
-        private T GetValue<T>(ParseResult parseResult, CliArgument<T> argument)
+        private static T GetValue<T>(ParseResult parseResult, CliArgument<T> argument)
             => parseResult.GetValue(argument);
 
         //[Fact]
@@ -1921,5 +1919,24 @@ public void ParseResult_contains_option_ValueResults()
             result1.GetValue<string>().Should().Be("Kirk");
             result2.GetValue<string>().Should().Be("Spock");
         }
+
+        // https://github.com/dotnet/command-line-api/issues/2392
+        [Fact]
+        public void Getting_argument_value_with_option_argument_error_the_only_a_single_error_is_returned()
+        {
+            var option = new CliOption<int[]>("-x") { Arity = new ArgumentArity(2, 3), AllowMultipleArgumentsPerToken = true };
+            var command = new CliCommand("the-command")
+            {
+                option
+            };
+
+            ParseResult parseResult = CliParser.Parse(command, "-x 1 2 3 4");
+
+            _ = parseResult.CommandResult.GetValue(option);
+
+            parseResult.Errors
+                       .Should()
+                       .ContainSingle();
+        }
     }
 }

src/System.CommandLine/Parsing/ArgumentResult.cs

@@ -31,10 +31,11 @@ public ValueResult ValueResult
                 {
                     // This is not lazy on the assumption that almost everything the user enters will be used, and ArgumentResult is no longer used for defaults
                     // TODO: Make sure errors are added
-                    var conversionValue = GetArgumentConversionResult().Value;
+                    ArgumentConversionResult argumentConversionValue = GetArgumentConversionResult();
+                    var conversionValue = argumentConversionValue.Value;
                     var locations = Tokens.Select(token => token.Location).ToArray();
                     //TODO: Remove this wrapper later
-                    _valueResult = new ValueResult(Argument, conversionValue, locations, ArgumentResult.GetValueResultOutcome(GetArgumentConversionResult()?.Result)); // null is temporary here
+                    _valueResult = new ValueResult(Argument, conversionValue, locations, GetValueResultOutcome(argumentConversionValue.Result));
                 }
                 return _valueResult;
             }

src/System.CommandLine/Parsing/OptionResult.cs

@@ -37,7 +37,7 @@ public ValueResult ValueResult
                     var conversionValue = ArgumentConversionResult.Value;
                     var locations = Tokens.Select(token => token.Location).ToArray();
                     //TODO: Remove this wrapper later
-                    _valueResult = new ValueResult(Option, conversionValue, locations, ArgumentResult.GetValueResultOutcome(ArgumentConversionResult?.Result)); // null is temporary here
+                    _valueResult = new ValueResult(Option, conversionValue, locations, ArgumentResult.GetValueResultOutcome(ArgumentConversionResult.Result));
                 }
                 return _valueResult;
             }

src/System.CommandLine/Parsing/SymbolResultTree.cs

@@ -15,7 +15,7 @@ internal sealed class SymbolResultTree : Dictionary<CliSymbol, SymbolResult>
         internal List<CliToken>? UnmatchedTokens;
 */
 
-        // TODO: Looks like this is a SymboNode/linked list because a symbol may appear multiple
+        // TODO: Looks like this is a SymbolNode/linked list because a symbol may appear multiple
         // places in the tree and multiple symbols will have the same short name. The question is 
         // whether creating the multiple node instances is faster than just using lists. Could well be.
         private Dictionary<string, SymbolNode>? _symbolsByName;