fix: not able to declare opportunity lost without competitors (#29531)

diff --git a/erpnext/selling/sales_common.js b/erpnext/selling/sales_common.js
index bd3b41f..16e3847 100644
--- a/erpnext/selling/sales_common.js
+++ b/erpnext/selling/sales_common.js
@@ -499,7 +499,7 @@
 					method: 'declare_enquiry_lost',
 					args: {
 						'lost_reasons_list': values.lost_reason,
-						'competitors': values.competitors,
+						'competitors': values.competitors ? values.competitors : [],
 						'detailed_reason': values.detailed_reason
 					},
 					callback: function(r) {