fix: column 'outstanding_amount' cannot be null (#26371)

diff --git a/erpnext/accounts/doctype/payment_entry/payment_entry.py b/erpnext/accounts/doctype/payment_entry/payment_entry.py
index adaf99a..0c21aae 100644
--- a/erpnext/accounts/doctype/payment_entry/payment_entry.py
+++ b/erpnext/accounts/doctype/payment_entry/payment_entry.py
@@ -1318,9 +1318,9 @@
 
 	return frappe._dict({
 		"due_date": ref_doc.get("due_date"),
-		"total_amount": total_amount,
-		"outstanding_amount": outstanding_amount,
-		"exchange_rate": exchange_rate,
+		"total_amount": flt(total_amount),
+		"outstanding_amount": flt(outstanding_amount),
+		"exchange_rate": flt(exchange_rate),
 		"bill_no": bill_no
 	})