[enhancement] improve visibility into error status codes

[axiomofjoy]

Improve Visibility into Error Status Codes

Error status codes on children spans are not propagated upward to parent spans in the UI. This causes a usability issue where users cannot identify traces that contain exceptions without exploding the traces into their constituent spans.

What it Looks Like

Collapsed Traces

No error status code is shown even though one of the traces has an exception.

Exploded Traces

The exception is visible once you explode the traces.

Spans

Only the span containing the exception event has a status code in the UI.

Tree

The ancestor spans in the trace tree do not have error status codes.

Note

This issue does not affect the LangChain tracer since LangChain's tracer class propagates error information up the tree for us.

Originally posted by @axiomofjoy in #1618 (comment)