show stack trace when export errors happen

Differential Revision: D30973518

fbshipit-source-id: fbdfb862ab23d5141553499471f92d2218addf91

tools/exporter.py

@@ -66,7 +66,7 @@ def main(
             logger.info(f"Predictor type {typ} has been exported to {predictor_path}")
             predictor_paths[typ] = predictor_path
         except Exception as e:
-            logger.warning(f"Export {typ} predictor failed: {e}")
+            logger.exception(f"Export {typ} predictor failed: {e}")
             if not skip_if_fail:
                 raise e