fix: better validation message for the expense claim and set default cost center in the expenses table (#21454)

diff --git a/erpnext/hr/doctype/expense_claim/expense_claim.js b/erpnext/hr/doctype/expense_claim/expense_claim.js
index 88f3865..fb23103 100644
--- a/erpnext/hr/doctype/expense_claim/expense_claim.js
+++ b/erpnext/hr/doctype/expense_claim/expense_claim.js
@@ -17,7 +17,7 @@
 			return;
 		}
 		return frappe.call({
-			method: "erpnext.hr.doctype.expense_claim.expense_claim.get_expense_claim_account",
+			method: "erpnext.hr.doctype.expense_claim.expense_claim.get_expense_claim_account_and_cost_center",
 			args: {
 				"expense_claim_type": d.expense_type,
 				"company": doc.company
@@ -25,6 +25,7 @@
 			callback: function(r) {
 				if (r.message) {
 					d.default_account = r.message.account;
+					d.cost_center = r.message.cost_center;
 				}
 			}
 		});
diff --git a/erpnext/hr/doctype/expense_claim/expense_claim.py b/erpnext/hr/doctype/expense_claim/expense_claim.py
index fe8afdf..ad9d86b 100644
--- a/erpnext/hr/doctype/expense_claim/expense_claim.py
+++ b/erpnext/hr/doctype/expense_claim/expense_claim.py
@@ -2,9 +2,9 @@
 # License: GNU General Public License v3. See license.txt
 
 from __future__ import unicode_literals
-import frappe
+import frappe, erpnext
 from frappe import _
-from frappe.utils import get_fullname, flt, cstr
+from frappe.utils import get_fullname, flt, cstr, get_link_to_form
 from frappe.model.document import Document
 from erpnext.hr.utils import set_employee_name
 from erpnext.accounts.party import get_party_account
@@ -192,7 +192,8 @@
 	def validate_account_details(self):
 		for data in self.expenses:
 			if not data.cost_center:
-				frappe.throw(_("Cost center is required to book an expense claim"))
+				frappe.throw(_("Row {0}: {1} is required in the expenses table to book an expense claim.")
+					.format(data.idx, frappe.bold("Cost Center")))
 
 		if self.is_paid:
 			if not self.mode_of_payment:
@@ -309,12 +310,22 @@
 	return je.as_dict()
 
 @frappe.whitelist()
+def get_expense_claim_account_and_cost_center(expense_claim_type, company):
+	data = get_expense_claim_account(expense_claim_type, company)
+	cost_center = erpnext.get_default_cost_center(company)
+
+	return {
+		"account": data.get("account"),
+		"cost_center": cost_center
+	}
+
+@frappe.whitelist()
 def get_expense_claim_account(expense_claim_type, company):
 	account = frappe.db.get_value("Expense Claim Account",
 		{"parent": expense_claim_type, "company": company}, "default_account")
 	if not account:
-		frappe.throw(_("Please set default account in Expense Claim Type {0}")
-			.format(expense_claim_type))
+		frappe.throw(_("Set the default account for the {0} {1}")
+			.format(frappe.bold("Expense Claim Type"), get_link_to_form("Expense Claim Type", expense_claim_type)))
 
 	return {
 		"account": account