fix: Do no query GLs if no PCVs are posted

(cherry picked from commit f4d1a54588)

erpnext/patches/v14_0/update_closing_balances.py

@@ -18,6 +18,8 @@ def execute():
 	frappe.db.truncate("Account Closing Balance")
 
 	pcv_list = get_period_closing_vouchers()
+
+	if pcv_list:
 		gl_entries = get_gl_entries(pcv_list)
 
 		for _, pcvs in itertools.groupby(pcv_list, key=lambda pcv: (pcv.company, pcv.period_start_date)):