show message if there's no submitted salary slip
diff --git a/erpnext/hr/doctype/process_payroll/process_payroll.py b/erpnext/hr/doctype/process_payroll/process_payroll.py
index 287ce61..a2d5d3e 100644
--- a/erpnext/hr/doctype/process_payroll/process_payroll.py
+++ b/erpnext/hr/doctype/process_payroll/process_payroll.py
@@ -339,7 +339,12 @@
 					"debit_in_account_currency": total_salary_amount.rounded_total
 				})	
 			journal_entry.set("accounts", account_amt_list)
-		return journal_entry.as_dict()
+			return journal_entry.as_dict()
+		else:
+			frappe.msgprint(
+				"There are no submitted Salary Slips to process.",
+				title="Error"
+			)
 
 	def update_salary_slip_status(self, jv_name = None):
 		ss_list = self.get_sal_slip_list(ss_status=1)