instr(kafka): Log message type on send error (#1477)

From our statsd metrics it looks like it's not metrics that causes kafka
messages that are too large. Let's verify this with a sentry error
tagged by message type.

Author: jjbayer

relay-server/src/actors/store.rs

@@ -178,9 +178,13 @@ impl Producer {
         };
         let record = BaseRecord::to(topic_name).key(&key).payload(&serialized);
 
-        producer
-            .send(record)
-            .map_err(|(kafka_error, _message)| StoreError::SendFailed(kafka_error))
+        producer.send(record).map_err(|(kafka_error, _message)| {
+            relay_log::with_scope(
+                |scope| scope.set_tag("variant", message.variant()),
+                || relay_log::error!("error sending kafka message: {}", kafka_error),
+            );
+            StoreError::SendFailed(kafka_error)
+        })
     }
 }