fix: set item uom as stock_uom if it isn't set (#27623)

* fix: set item uom as stock_uom if it isn't set
diff --git a/erpnext/stock/doctype/stock_entry/stock_entry.js b/erpnext/stock/doctype/stock_entry/stock_entry.js
index 157904b..ac8303e 100644
--- a/erpnext/stock/doctype/stock_entry/stock_entry.js
+++ b/erpnext/stock/doctype/stock_entry/stock_entry.js
@@ -323,6 +323,12 @@
 		attach_bom_items(frm.doc.bom_no)
 	},
 
+	before_save: function(frm) {
+		frm.doc.items.forEach((item) => {
+			item.uom = item.uom || item.stock_uom;
+		})
+	},
+
 	stock_entry_type: function(frm){
 		frm.remove_custom_button('Bill of Materials', "Get Items From");
 		frm.events.show_bom_custom_button(frm);