ETW Exporter: Crash When Ending ETW Exporter Span

The same code works correctly when using the OpenTelemetry Tracer, Span, and OTLP Exporter. However, the application crashes when switching to the ETW Exporter.

Code to Reproduce (ETW Exporter)

  void TestEtwTracer()
  {
    auto traceProvider = std::make_unique<opentelemetry::exporter::etw::TracerProvider>();
    auto tracer = traceProvider->GetTracer("Geneva-Tracer-Foo");
    auto spanFoo = tracer->StartSpan("Span-Foo");
    tracer = traceProvider->GetTracer("Geneva-Tracer-Bar");
    auto spanBar = tracer->StartSpan("Span-Bar");
    spanFoo->End();
    spanBar->End();
  }

Crash Screenshot

Code to Reproduce (OTLP Exporter – Works as Expected)

  void TestOTelTracer()
  {
    auto ostream_exporter = opentelemetry::exporter::trace::OStreamSpanExporterFactory::Create();
    auto ostream_processor = opentelemetry::sdk::trace::SimpleSpanProcessorFactory::Create(std::move(ostream_exporter));

    std::vector<std::unique_ptr<opentelemetry::sdk::trace::SpanProcessor>> processors;
    processors.push_back(std::move(ostream_processor));

    auto resource_attributes = opentelemetry::sdk::resource::ResourceAttributes{ {"service.name", "Test OTel"} };
    auto resource_ptr = opentelemetry::sdk::resource::Resource::Create(resource_attributes);

    std::unique_ptr<opentelemetry::sdk::trace::TracerContext> context =
      opentelemetry::sdk::trace::TracerContextFactory::Create(std::move(processors), resource_ptr);

    auto traceProvider = opentelemetry::sdk::trace::TracerProviderFactory::Create(std::move(context));
    auto tracer = traceProvider->GetTracer("OTel-Tracer-Foo");
    auto spanFoo = tracer->StartSpan("Span-Foo");

    tracer = traceProvider->GetTracer("OTel-Tracer-Bar");
    auto spanBar = tracer->StartSpan("Span-Bar");
    spanFoo->End();
    spanBar->End();
  }

Screenshot (No Crash)

The issue names no files or tests. Start by running the ETW exporter reproducer and tracing the span-end path, then compare it with the working OTLP setup to locate the crash. Done means both ETW spans can end without crashing, ideally covered by a regression test.