Change error message to use posix group token, fixes #2

Author: daningalla

src/lib/Vertical/Cli/Parsing/ParseResult.Create.cs

@@ -134,7 +134,7 @@ private static int ParseOptionToken(
 
         if (!optionSymbols.TryGetValue(symbol, out var option))
         {
-            state.Errors.Add(new InvalidOptionSymbolError(semanticToken.ConstituentToken));
+            state.Errors.Add(new InvalidOptionSymbolError(semanticToken.Token));
             return 0;
         }