fix: Add breadcrumbs before early return in pymongo streaming path

Same issue as asyncpg/aiomysql — the no-current-span guard was
skipping breadcrumb creation. Move breadcrumb and data computation
before the guard.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sentrivana

sentry_sdk/integrations/pymongo.py

@@ -152,9 +152,6 @@ def started(self, event: "CommandStartedEvent") -> None:
             query = json.dumps(command, default=str)
 
             if has_span_streaming_enabled(client.options):
-                if sentry_sdk.traces.get_current_span() is None:
-                    return
-
                 span_first_data = {
                     "db.operation.name": operation_name,
                     "db.collection.name": collection_name,
@@ -164,10 +161,6 @@ def started(self, event: "CommandStartedEvent") -> None:
                     **db_data,
                 }
 
-                span = sentry_sdk.traces.start_span(
-                    name=query, attributes=span_first_data
-                )
-
                 with capture_internal_exceptions():
                     sentry_sdk.add_breadcrumb(
                         message=query,
@@ -176,6 +169,13 @@ def started(self, event: "CommandStartedEvent") -> None:
                         data=span_first_data,
                     )
 
+                if sentry_sdk.traces.get_current_span() is None:
+                    return
+
+                span = sentry_sdk.traces.start_span(
+                    name=query, attributes=span_first_data
+                )
+
             else:
                 tags = {
                     "db.name": db_name,