[Fix] Bank Account mandatory (#14734)

erpnext/accounts/doctype/bank_statement_transaction_entry/bank_statement_transaction_entry.py

@@ -25,6 +25,7 @@ class BankStatementTransactionEntry(Document):
 		mapper = frappe.new_doc("Bank Statement Settings")
 		mapper.bank = bank
 		mapper.date_format = "%Y-%m-%d"
+		mapper.bank_account = self.bank_account
 		for header in ["Date", "Particulars", "Withdrawals", "Deposits", "Balance"]:
 			header_item = mapper.append("header_items", {})
 			header_item.mapped_header = header_item.stmt_header = header
@@ -40,6 +41,10 @@ class BankStatementTransactionEntry(Document):
 		else:
 			self.match_invoice_to_payment()
 
+	def validate(self):
+		if not self.new_transaction_items:
+			self.populate_payment_entries()
+
 	def get_statement_headers(self):
 		if not self.bank_settings:
 			frappe.throw("Bank Data mapper doesn't exist")