updates per review

Author: david-leifker

docs/how/updating-datahub.md

@@ -36,6 +36,7 @@ This file documents any backwards-incompatible changes in DataHub and assists pe
 ### Known Issues
 
 - #12601: Jetty 12 introduces a stricter handling of url encoding. We are currently applying a workaround to prevent a regression, while technically breaking the official specifications.
+- #12714: API Tracing requires at least one mutation of the aspect being updated using this version of DataHub.
 
 ### Potential Downtime
 

metadata-ingestion/src/datahub/emitter/rest_emitter.py

@@ -113,6 +113,7 @@ class RestSinkEndpoint(ConfigEnum):
 )
 
 
+# Supported with v1.0
 DEFAULT_REST_TRACE_MODE = pydantic.parse_obj_as(
     RestTraceMode,
     os.getenv("DATAHUB_REST_TRACE_MODE", RestTraceMode.DISABLED),
@@ -456,7 +457,7 @@ def emit_mcp(
             response = self._emit_generic(url, payload)
 
             if self._should_trace(async_flag, trace_flag):
-                trace_data = extract_trace_data_from_mcps(response, [mcp])
+                trace_data = extract_trace_data_from_mcps(response, [mcp]) if response else None
 
         if trace_data:
             self._await_status(