When set_span_errored is called on a NoOpStreamedSpan, accessing span._segment at line 1122 will raise an AttributeError. NoOpStreamedSpan.__init__ (traces.py:538-548) does not call the parent StreamedSpan.__init__, so the _segment slot attribute is never initialized. Since _segment is defined in StreamedSpan.__slots__, accessing it without initialization raises AttributeError: '_segment'.

The set_span_errored function checks isinstance(span, StreamedSpan) which is True for NoOpStreamedSpan instances since it inherits from StreamedSpan. However, NoOpStreamedSpan.__init__ does not call super().__init__() and does not initialize the _segment attribute. When set_span_errored accesses span._segment, it will raise an AttributeError for NoOpStreamedSpan instances. This can occur when tracing is disabled but the function is still called.