The code checks isinstance(current_span, StreamedSpan) but NoOpStreamedSpan is a subclass of StreamedSpan that does NOT initialize the _segment attribute in its __init__. When traces_sample_rate < 1.0 or spans are ignored, the current span can be a NoOpStreamedSpan, and accessing current_span._segment will raise an AttributeError. Other code in the codebase uses the pattern isinstance(span, StreamedSpan) and not isinstance(span, NoOpStreamedSpan) to handle this.