fix: Serial Nos not set in the row after scanning in popup

- Avoid whitspaces while calculating length of serial nos
diff --git a/erpnext/selling/sales_common.js b/erpnext/selling/sales_common.js
index ddd4c4e..a86e604 100644
--- a/erpnext/selling/sales_common.js
+++ b/erpnext/selling/sales_common.js
@@ -206,8 +206,10 @@
 		var me = this;
 		var item = frappe.get_doc(cdt, cdn);
 
-		if (item.serial_no && item.qty === item.serial_no.split(`\n`).length) {
-			return;
+		// check if serial nos entered are as much as qty in row
+		if (item.serial_no) {
+			let serial_nos = item.serial_no.split(`\n`).filter(sn => sn.trim()); // filter out whitespaces
+			if (item.qty === serial_nos.length) return;
 		}
 
 		if (item.serial_no && !item.batch_no) {