Print errors from response on metadata upload

upload/upload.py

@@ -156,6 +156,17 @@ for record in records:
                 data=content,
                 headers=auth_json_header,
             )
+
+            # errors in the metadata are reported via the "errors" field in the response
+            if data and "errors" in data:
+                print(
+                    "errors from response at step '{}' while processing '{}':".format(
+                        step, record
+                    ),
+                    file=sys.stderr,
+                )
+                print(data["errors"], file=sys.stderr)
+
             recid = data["id"]
 
         # if there are any files to be uploaded, invenio needs to know about them