[Bug-Fix] Cannot Save Bank Statement Transaction Entry (#15793)

* Create bank settings only if bank name is available

* Minor bug-fix in validate_overlap
diff --git a/erpnext/accounts/doctype/bank_statement_transaction_entry/bank_statement_transaction_entry.py b/erpnext/accounts/doctype/bank_statement_transaction_entry/bank_statement_transaction_entry.py
index 7a7d7d2..f558194 100644
--- a/erpnext/accounts/doctype/bank_statement_transaction_entry/bank_statement_transaction_entry.py
+++ b/erpnext/accounts/doctype/bank_statement_transaction_entry/bank_statement_transaction_entry.py
@@ -16,10 +16,11 @@
 class BankStatementTransactionEntry(Document):
 	def autoname(self):
 		self.name = self.bank_account + "-" + self.from_date + "-" + self.to_date
-		mapper_name = self.bank + "-Statement-Settings"
-		if not frappe.db.exists("Bank Statement Settings", mapper_name):
-			self.create_settings(self.bank)
-		self.bank_settings = mapper_name
+		if self.bank:
+			mapper_name = self.bank + "-Statement-Settings"
+			if not frappe.db.exists("Bank Statement Settings", mapper_name):
+				self.create_settings(self.bank)
+			self.bank_settings = mapper_name
 
 	def create_settings(self, bank):
 		mapper = frappe.new_doc("Bank Statement Settings")
diff --git a/erpnext/hr/utils.py b/erpnext/hr/utils.py
index 281b7fc..f35eb59 100644
--- a/erpnext/hr/utils.py
+++ b/erpnext/hr/utils.py
@@ -178,7 +178,8 @@
 		}, as_dict = 1)
 
 	if overlap_doc:
-		exists_for = doc.employee
+		if doc.get("employee"):
+			exists_for = doc.employee
 		if company:
 			exists_for = company
 		throw_overlap_error(doc, exists_for, overlap_doc[0].name, from_date, to_date)