log and bail if stacktrace string is empty

src/sentry/seer/similarity/similar_issues.py

@@ -66,6 +66,29 @@ def get_similarity_data_from_seer(
                 "referrer": similar_issues_request.get("referrer"),
             },
         )
+    # TODO: This is temporary, to debug Seer being sent empty stacktraces (which will happen for
+    # ingest requests if the filter in `event_content_is_seer_eligible` for existence of frames
+    # isn't enough, or if the similar issues tab ever sends an empty stacktrace). If we want this
+    # check to become permanent, we should move it elsewhere.
+    if not similar_issues_request["stacktrace"]:
+        logger.warning(
+            "get_seer_similar_issues.empty_stacktrace",
+            extra={
+                "event_id": similar_issues_request["event_id"],
+                "project_id": similar_issues_request["project_id"],
+                "hash": similar_issues_request["hash"],
+                "referrer": similar_issues_request.get("referrer"),
+            },
+        )
+        metrics.incr(
+            "seer.similar_issues_request",
+            sample_rate=SIMILARITY_REQUEST_METRIC_SAMPLE_RATE,
+            tags={
+                **metric_tags,
+                "outcome": "empty_stacktrace",
+            },
+        )
+        return []
 
     response = make_signed_seer_api_request(
         seer_grouping_connection_pool,