fix: broken overallocation validation in payment entry

In a multi term payment schedule, overallocation logic broke. Fixing
it using individual term outstanding amount in references. this should
work for the simple, one term payment schedule as well

(cherry picked from commit f8d4b19)

erpnext/accounts/doctype/payment_entry/payment_entry.py

@@ -182,10 +182,12 @@ def validate_allocated_amount_with_latest_data(self):
 		latest_lookup = {}
 		for d in latest_references:
 			d = frappe._dict(d)
-			latest_lookup.update({(d.voucher_type, d.voucher_no): d})
+			latest_lookup.setdefault((d.voucher_type, d.voucher_no), frappe._dict())[d.payment_term] = d
 
 		for d in self.get("references"):
-			latest = latest_lookup.get((d.reference_doctype, d.reference_name))
+			latest = (latest_lookup.get((d.reference_doctype, d.reference_name)) or frappe._dict()).get(
+				d.payment_term
+			)
 
 			# The reference has already been fully paid
 			if not latest:
@@ -208,6 +210,18 @@ def validate_allocated_amount_with_latest_data(self):
 			if (flt(d.allocated_amount)) > 0 and flt(d.allocated_amount) > flt(latest.outstanding_amount):
 				frappe.throw(fail_message.format(d.idx))
 
+			if d.payment_term and (
+				(flt(d.allocated_amount)) > 0
+				and flt(d.allocated_amount) > flt(latest.payment_term_outstanding)
+			):
+				frappe.throw(
+					_(
+						"Row #{0}: Allocated amount:{1} is greater than outstanding amount:{2} for Payment Term {3}"
+					).format(
+						d.idx, d.allocated_amount, latest.payment_term_outstanding, d.payment_term
+					)
+				)
+
 			# Check for negative outstanding invoices as well
 			if flt(d.allocated_amount) < 0 and flt(d.allocated_amount) < flt(latest.outstanding_amount):
 				frappe.throw(fail_message.format(d.idx))
@@ -1466,6 +1480,7 @@ def split_invoices_based_on_payment_terms(outstanding_invoices):
 										"posting_date": d.posting_date,
 										"invoice_amount": flt(d.invoice_amount),
 										"outstanding_amount": flt(d.outstanding_amount),
+										"payment_term_outstanding": flt(payment_term.outstanding),
 										"payment_amount": payment_term.payment_amount,
 										"payment_term": payment_term.payment_term,
 									}
@@ -2240,6 +2255,7 @@ def get_reference_as_per_payment_terms(
 					"due_date": doc.get("due_date"),
 					"total_amount": grand_total,
 					"outstanding_amount": outstanding_amount,
+					"payment_term_outstanding": payment_term_outstanding,
 					"payment_term": payment_term.payment_term,
 					"allocated_amount": payment_term_outstanding,
 				}