fix: return early from AddSentryOtlpExporter when DSN is the disable-SDK sentinel (#5247)

When the caller passes `SentryConstants.DisableSdkDsnValue` (empty string) to
`AddSentryOtlpExporter`, we now short-circuit before attempting to parse it as
a real DSN. This prevents a spurious `ArgumentException` when the SDK is
intentionally disabled.

Fixes #5246

Signed-off-by: James Crosswell <james.crosswell@gmail.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jamescrosswell

src/Sentry.OpenTelemetry.Exporter/SentryTracerProviderBuilderExtensions.cs

@@ -42,6 +42,11 @@ public static class SentryTracerProviderBuilderExtensions
     public static TracerProviderBuilder AddSentryOtlpExporter(this TracerProviderBuilder tracerProviderBuilder,
         string dsnString, Uri? collectorUrl = null, TextMapPropagator? defaultTextMapPropagator = null)
     {
+        if (Dsn.IsDisabled(dsnString))
+        {
+            return tracerProviderBuilder;
+        }
+
         if (Dsn.TryParse(dsnString) is not { } dsn)
         {
             throw new ArgumentException(MissingDsnWarning, nameof(dsnString));

test/Sentry.OpenTelemetry.Exporter.Tests/SentryTracerProviderBuilderExtensionsTests.cs

@@ -7,7 +7,6 @@ public class SentryTracerProviderBuilderExtensionsTests
 {
     [Theory]
     [InlineData(null)]
-    [InlineData("")]
     [InlineData("foo")]
     public void AddSentryOtlpExporter_InvalidDsn_ThrowsArgumentException(string dsn)
     {
@@ -22,6 +21,20 @@ public void AddSentryOtlpExporter_InvalidDsn_ThrowsArgumentException(string dsn)
             .WithMessage($"{SentryTracerProviderBuilderExtensions.MissingDsnWarning}*");
     }
 
+    [Fact]
+    public void AddSentryOtlpExporter_DisabledSdkDsn_ReturnsWithoutConfiguringExporter()
+    {
+        // Arrange
+        var tracerProviderBuilder = Substitute.For<TracerProviderBuilder>();
+
+        // Act
+        var result = tracerProviderBuilder.AddSentryOtlpExporter(SentryConstants.DisableSdkDsnValue);
+
+        // Assert
+        result.Should().BeSameAs(tracerProviderBuilder);
+        tracerProviderBuilder.DidNotReceive().AddInstrumentation(Arg.Any<Func<object>>());
+    }
+
     [Fact]
     public void OtlpConfigurationCallback_WithCustomCollectorUrl_SetsEndpointToCustomUrl()
     {