fix: report invalid MQTT and ROS2 binding scalars as errors

Several MQTT and ROS2 binding fields were parsed with
Get*ValueOrDefault(), which returns null for a value that cannot be
parsed. A document with e.g. `cleanSession: yes-please` or
`keepAlive: abc` was read with no diagnostics and the value was silently
dropped, so writing it back lost data.

These fields now use GetIntegerValue()/GetBooleanValue(), which report
"Value could not parse to ..." in diagnostic.Errors, matching the other
bindings (IBM MQ, JMS, Kafka, ...):

- MQTT server: cleanSession, keepAlive, lastWill.qos
- MQTT message: payloadFormatIndicator
- ROS2 server: domainId
- ROS2 QoS policies: lifespan, deadline, leaseDuration

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

Author: 2 people

src/ByteBard.AsyncAPI.Bindings/MQTT/MQTTMessageBinding.cs

@@ -97,7 +97,7 @@ private void SerializeProperties(IAsyncApiWriter writer, AsyncApiVersion version
         protected override FixedFieldMap<MQTTMessageBinding> FixedFieldMap => new()
         {
             { "bindingVersion", (a, n) => { a.BindingVersion = n.GetScalarValue(); } },
-            { "payloadFormatIndicator", (a, n) => { a.PayloadFormatIndicator = n.GetIntegerValueOrDefault(); } },
+            { "payloadFormatIndicator", (a, n) => { a.PayloadFormatIndicator = n.GetIntegerValue(); } },
             { "correlationData", (a, n) => { a.CorrelationData = AsyncApiJsonSchemaDeserializer.LoadSchema(n); } },
             { "contentType", (a, n) => { a.ContentType = n.GetScalarValue(); } },
             { "responseTopic", (a, n) => { a.ResponseTopicValue = MQTTStringOrSchema.Parse(n); } },

src/ByteBard.AsyncAPI.Bindings/MQTT/MQTTServerBinding.cs

@@ -65,17 +65,17 @@ public int? MaximumPacketSize
         {
             { "bindingVersion", (a, n) => { a.BindingVersion = n.GetScalarValue(); } },
             { "clientId", (a, n) => { a.ClientId = n.GetScalarValue(); } },
-            { "cleanSession", (a, n) => { a.CleanSession = n.GetBooleanValueOrDefault(); } },
+            { "cleanSession", (a, n) => { a.CleanSession = n.GetBooleanValue(); } },
             { "lastWill", (a, n) => { a.LastWill = n.ParseMap(LastWillFixedFields); } },
-            { "keepAlive", (a, n) => { a.KeepAlive = n.GetIntegerValueOrDefault(); } },
+            { "keepAlive", (a, n) => { a.KeepAlive = n.GetIntegerValue(); } },
             { "sessionExpiryInterval", (a, n) => { a.SessionExpiryIntervalValue = MQTTIntegerOrSchema.Parse(n); } },
             { "maximumPacketSize", (a, n) => { a.MaximumPacketSizeValue = MQTTIntegerOrSchema.Parse(n); } },
         };
 
         private static FixedFieldMap<LastWill> LastWillFixedFields = new()
         {
             { "topic", (a, n) => { a.Topic = n.GetScalarValue(); } },
-            { "qos", (a, n) => { a.QoS = (uint?)n.GetIntegerValueOrDefault(); } },
+            { "qos", (a, n) => { a.QoS = (uint?)n.GetIntegerValue(); } },
             { "message", (a, n) => { a.Message = n.GetScalarValue(); } },
             { "retain", (a, n) => { a.Retain = n.GetBooleanValue(); } },
         };

src/ByteBard.AsyncAPI.Bindings/ROS2/ROS2QosPolicies.cs

@@ -21,10 +21,10 @@ public class ROS2QosPolicies : IAsyncApiElement
             { "reliability", (a, n) => { a.Reliability = n.GetScalarValue(); } },
             { "history", (a, n) => { a.History = n.GetScalarValue(); } },
             { "durability", (a, n) => { a.Durability = n.GetScalarValue(); } },
-            { "lifespan", (a, n) => { a.Lifespan = n.GetIntegerValueOrDefault(); } },
-            { "deadline", (a, n) => { a.Deadline = n.GetIntegerValueOrDefault(); } },
+            { "lifespan", (a, n) => { a.Lifespan = n.GetIntegerValue(); } },
+            { "deadline", (a, n) => { a.Deadline = n.GetIntegerValue(); } },
             { "liveliness", (a, n) => { a.Liveliness = n.GetScalarValue(); } },
-            { "leaseDuration", (a, n) => { a.LeaseDuration = n.GetIntegerValueOrDefault(); } },
+            { "leaseDuration", (a, n) => { a.LeaseDuration = n.GetIntegerValue(); } },
         };
 
         /// <summary>

src/ByteBard.AsyncAPI.Bindings/ROS2/ROS2ServerBinding.cs

@@ -18,7 +18,7 @@ public class ROS2ServerBinding : ServerBinding<ROS2ServerBinding>
         protected override FixedFieldMap<ROS2ServerBinding> FixedFieldMap => new()
         {
             { "rmwImplementation", (a, n) => { a.RmwImplementation = n.GetScalarValue(); } },
-            { "domainId", (a, n) => { a.DomainId = n.GetIntegerValueOrDefault(); } },
+            { "domainId", (a, n) => { a.DomainId = n.GetIntegerValue(); } },
         };
 
         /// <summary>

test/ByteBard.AsyncAPI.Tests/Bindings/BindingInvalidScalars_Should.cs

@@ -0,0 +1,69 @@
+namespace ByteBard.AsyncAPI.Tests.Bindings
+{
+    using FluentAssertions;
+    using ByteBard.AsyncAPI.Bindings;
+    using ByteBard.AsyncAPI.Models;
+    using ByteBard.AsyncAPI.Readers;
+    using NUnit.Framework;
+
+    internal class BindingInvalidScalars_Should : TestBase
+    {
+        [TestCase("mqtt", "cleanSession: yes-please", "bool")]
+        [TestCase("mqtt", "keepAlive: abc", "integer")]
+        [TestCase("mqtt", "lastWill:\n  topic: /wills\n  qos: high", "integer")]
+        [TestCase("ros2", "domainId: abc", "integer")]
+        public void ServerBinding_WithInvalidScalar_ReportsError(string bindingKey, string field, string expectedType)
+        {
+            var yaml =
+                "host: localhost\n" +
+                "protocol: " + bindingKey + "\n" +
+                "bindings:\n" +
+                "  " + bindingKey + ":\n" +
+                Indent(field, 4);
+
+            new AsyncApiStringReader(Settings()).ReadFragment<AsyncApiServer>(yaml, AsyncApiVersion.AsyncApi3_0, out var diagnostics);
+
+            diagnostics.Errors.Should().ContainSingle().Which.Message.Should().Contain($"could not parse to {expectedType}");
+        }
+
+        [Test]
+        public void MessageBinding_WithInvalidPayloadFormatIndicator_ReportsError()
+        {
+            var yaml =
+                "bindings:\n" +
+                "  mqtt:\n" +
+                "    payloadFormatIndicator: abc\n";
+
+            new AsyncApiStringReader(Settings()).ReadFragment<AsyncApiMessage>(yaml, AsyncApiVersion.AsyncApi3_0, out var diagnostics);
+
+            diagnostics.Errors.Should().ContainSingle().Which.Message.Should().Contain("could not parse to integer");
+        }
+
+        [TestCase("lifespan")]
+        [TestCase("deadline")]
+        [TestCase("leaseDuration")]
+        public void ROS2OperationBinding_WithInvalidQosDuration_ReportsError(string field)
+        {
+            var yaml =
+                "action: send\n" +
+                "channel:\n" +
+                "  $ref: '#/channels/camera'\n" +
+                "bindings:\n" +
+                "  ros2:\n" +
+                "    qosPolicies:\n" +
+                "      " + field + ": forever\n";
+
+            new AsyncApiStringReader(Settings()).ReadFragment<AsyncApiOperation>(yaml, AsyncApiVersion.AsyncApi3_0, out var diagnostics);
+
+            diagnostics.Errors.Should().ContainSingle().Which.Message.Should().Contain("could not parse to integer");
+        }
+
+        private static AsyncApiReaderSettings Settings() => new() { Bindings = BindingsCollection.All };
+
+        private static string Indent(string value, int spaces)
+        {
+            var prefix = new string(' ', spaces);
+            return prefix + value.Replace("\n", "\n" + prefix) + "\n";
+        }
+    }
+}