fix: reload before saving on reconnect (#26534) (#26536)

The doc we have might be "in future".

(cherry picked from commit 9e9e72b)

Co-authored-by: Ankush Menat <ankush@frappe.io>

frappe/core/doctype/prepared_report/prepared_report.py

@@ -82,9 +82,8 @@ def generate_report(prepared_report):
 
 		instance.status = "Completed"
 	except Exception:
-		instance.status = "Error"
-		instance.error_message = frappe.get_traceback(with_context=True)
-		_save_instance(instance)  # we need to ensure that error gets stored
+		# we need to ensure that error gets stored
+		_save_error(instance, error=frappe.get_traceback(with_context=True))
 
 	instance.report_end_time = frappe.utils.now()
 	instance.save(ignore_permissions=True)
@@ -102,7 +101,10 @@ def update_job_id(prepared_report, job_id):
 
 
 @dangerously_reconnect_on_connection_abort
-def _save_instance(instance):
+def _save_error(instance, error):
+	instance.reload()
+	instance.status = "Error"
+	instance.error_message = error
 	instance.save(ignore_permissions=True)