[fix] log newsletter sending error

erpnext/tasks.py

@@ -4,6 +4,7 @@
 from __future__ import unicode_literals
 import frappe
 from frappe.celery_app import celery_task, task_logger
+from frappe.utils.scheduler import log
 
 @celery_task()
 def send_newsletter(site, newsletter, event):
@@ -15,12 +16,16 @@ def send_newsletter(site, newsletter, event):
 
 	except:
 		frappe.db.rollback()
-		task_logger.warn(frappe.get_traceback())
+
+		task_logger.error(site)
+		task_logger.error(frappe.get_traceback())
 
 		# wasn't able to send emails :(
 		doc.db_set("email_sent", 0)
 		frappe.db.commit()
 
+		log("send_newsletter")
+
 		raise
 
 	else: