fix: accept only unsigned digits as pointer array indices and strip one integer sign

Parse JSON pointer array tokens with NumberStyles.None and the invariant
culture, so tokens such as "-0", "+0" or " 0" no longer resolve to an element.
When explaining an invalid integer, strip at most one leading sign so values
such as "+-1" are reported as malformed rather than out of range.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: bielu

src/ByteBard.AsyncAPI.Readers/ParseNodes/JsonPointerExtensions.cs

@@ -1,5 +1,6 @@
 namespace ByteBard.AsyncAPI.Readers.ParseNodes
 {
+    using System.Globalization;
     using System.Text.Json.Nodes;
 
     public static class JsonPointerExtensions
@@ -16,7 +17,7 @@ public static JsonNode Find(this JsonPointer currentPointer, JsonNode baseJsonNo
             {
                 if (pointer is JsonArray sequence)
                 {
-                    if (!int.TryParse(token, out var index) || index < 0 || index >= sequence.Count)
+                    if (!int.TryParse(token, NumberStyles.None, CultureInfo.InvariantCulture, out var index) || index >= sequence.Count)
                     {
                         return null;
                     }

src/ByteBard.AsyncAPI.Readers/ParseNodes/ValueNode.cs

@@ -119,7 +119,12 @@ public override AsyncApiAny CreateAny()
         private string DescribeInvalidInteger(string typeName, long min, long max)
         {
             var value = this.GetScalarValue();
-            var digits = value?.Trim().TrimStart('+', '-');
+            var digits = value?.Trim();
+            if (digits?.Length > 0 && (digits[0] == '+' || digits[0] == '-'))
+            {
+                digits = digits.Substring(1);
+            }
+
             var isWholeNumber = !string.IsNullOrEmpty(digits) && digits.All(c => c >= '0' && c <= '9');
 
             return isWholeNumber

test/ByteBard.AsyncAPI.Tests/ReaderErrorDetails_Should.cs

@@ -11,7 +11,9 @@ internal class ReaderErrorDetails_Should : TestBase
     {
         [TestCase("abc", "Value 'abc' could not parse to integer. Expected a whole number.")]
         [TestCase("1.5", "Value '1.5' could not parse to integer. Expected a whole number.")]
-        [TestCase("99999999999", "Value '99999999999' could not parse to integer. It must be between -2147483648 and 2147483647.")]
+        [TestCase("+-1", "Value '+-1' could not parse to integer. Expected a whole number.")]
+        [TestCase("--1", "Value '--1' could not parse to integer. Expected a whole number.")]
+        [TestCase("99999999999","Value '99999999999' could not parse to integer. It must be between -2147483648 and 2147483647.")]
         public void SchemaIntegerField_ReportsTheValueAndWhyItIsInvalid(string value, string expectedMessage)
         {
             var yaml = $"type: string\nmaxLength: '{value}'";
@@ -49,6 +51,9 @@ public void MissingLocalReference_IsReportedOnce()
         [TestCase("/info/title/nested")]
         [TestCase("/tags/5")]
         [TestCase("/tags/name")]
+        [TestCase("/tags/-0")]
+        [TestCase("/tags/+0")]
+        [TestCase("/tags/ 0")]
         [TestCase("/missing")]
         public void Find_ReturnsNull_WhenThePointerDoesNotLeadToANode(string pointer)
         {