select client script is not working

ERPNext
1

this is the client script i am working i am fetching my mrp from item doctype when i am adding a new row the custom_mrp is getting fetched but after that whne again i am adding new row below that the first select option is getting autopopulated and 1 more issue is there that the in editing row custom_mrp is also not getting fetched

frappe.ui.form.on(‘Purchase Order’, {
refresh: function (frm) {
if (frm.doc.items && frm.doc.items.length) {
console.log(Found ${frm.doc.items.length} items to process);
frm.doc.items.forEach((item, index) => {
console.log(Processing item ${index + 1}: ${item.item_code});
if (item.item_code) {
updateMRPOptionsForItem(frm, item.doctype, item.name, item.item_code);
}
});
}
}
});

frappe.ui.form.on(‘Purchase Order Item’, {
item_code: function (frm, cdt, cdn) {
console.log(“Item code changed:”, cdn);
let item = locals[cdt][cdn];
if (item && item.item_code) {
console.log(Updating MRP for item: ${item.item_code});
updateMRPOptionsForItem(frm, cdt, cdn, item.item_code);
}
},

// Add this new method to reset MRP when a new row is added
before_items_add: function(frm, cdt, cdn) {
    let field = frappe.meta.get_docfield("Purchase Order Item", "custom_mrp");
    if (field) {
        field.options = '';
    }
}

});

function updateMRPOptionsForItem(frm, doctype, rowName, itemCode) {
console.log(Fetching MRP options for: ${itemCode});
if (!itemCode) {
console.log(“No item code provided, returning”);
return;
}

frappe.db.get_doc('Item', itemCode)
    .then(doc => {
        let mrpOptions = [''];  // Start with an empty option
        
        if (doc && doc.custom_mrp_ && Array.isArray(doc.custom_mrp_)) {
            mrpOptions = mrpOptions.concat(doc.custom_mrp_.map(mrpRow => `${mrpRow.mrp}`));
            console.log("MRP options found:", mrpOptions);
        } else {
            console.log("No MRP options found.");
        }
        
        let field = frappe.meta.get_docfield("Purchase Order Item", "custom_mrp");
        if (field) {
            field.options = mrpOptions.join("\n");
        }
        
        let row = frm.fields_dict.items.grid.grid_rows_by_docname[rowName];
        if (row) {
            row.refresh();
        }
        
        frm.refresh_field("items");
    })
    .catch(err => {
        console.error("Error fetching MRP options:", err);
        frappe.show_alert({
            message: `Failed to fetch MRP options for ${itemCode}`,
            indicator: 'red'
        });
    });

}