fix(setup wizard): Validate FY dates (#15419)

- start date should be less than end date
diff --git a/erpnext/public/js/setup_wizard.js b/erpnext/public/js/setup_wizard.js
index a030381..82d6f6e 100644
--- a/erpnext/public/js/setup_wizard.js
+++ b/erpnext/public/js/setup_wizard.js
@@ -141,9 +141,7 @@
 			let me = this;
 			let exist;
 
-			// validate fiscal year start and end dates
-			if (this.values.fy_start_date == 'Invalid date' || this.values.fy_end_date == 'Invalid date') {
-				frappe.msgprint(__("Please enter valid Financial Year Start and End Dates"));
+			if (!this.validate_fy_dates()) {
 				return false;
 			}
 
@@ -170,6 +168,20 @@
 			return true;
 		},
 
+		validate_fy_dates: function() {
+			// validate fiscal year start and end dates
+			const invalid = this.values.fy_start_date == 'Invalid date' ||
+				this.values.fy_end_date == 'Invalid date';
+			const start_greater_than_end = this.values.fy_start_date > this.values.fy_end_date;
+
+			if (invalid || start_greater_than_end) {
+				frappe.msgprint(__("Please enter valid Financial Year Start and End Dates"));
+				return false;
+			}
+
+			return true;
+		},
+
 		set_fy_dates: function (slide) {
 			var country = frappe.wizard.values.country;