fix(repost accounting ledger): prevent preview generation when no vouchers are selected

(cherry picked from commit bd9f5fca08)

erpnext/accounts/doctype/repost_accounting_ledger/repost_accounting_ledger.py

@@ -115,6 +115,10 @@ class RepostAccountingLedger(Document):
 	def generate_preview(self):
 		from erpnext.accounts.report.general_ledger.general_ledger import get_columns as get_gl_columns
 
+		if not self.vouchers:
+			frappe.msgprint(_("Add vouchers to generate preview."))
+			return
+
 		gl_columns = []
 		gl_data = []