hi .. now i try to inherit customer form view 'base.res_partner_form_view' using xml path

my xml

<odoo>
    <data>
        <record id="view_customers" model="ir.ui.view">
            <field name="name">View Customers</field>
            <field name="model">shop.customers</field>
            <field name="inherit_id" ref="base.view_partner_form"/>
            <field name="arch" type="xml">
                <xpath expr="//field[@name='name']" position="after">
                    <field name="customer_type" />
                </xpath>
            </field>
        </record>

        <record id="shop_customers_action" model="ir.actions.act_window">
            <field name="name">SHOP Customers</field>
            <field name="res_model">shop.customers</field>
            <field name="view_type">form</field>
            <field name="view_mode">tree,form</field>
        </record>
        <menuitem id="my_shop" name="MY SHOP"/>
        <menuitem id="shop_data" name="Shop Data" parent="my_shop"/>
        <menuitem id="customers" name="Customers" parent="shop_data" action="shop_customers_action"/>
    </data>
</odoo>
my model
class ShopCustomers(models.Model):
    _name = 'shop.customers'
    _inherit = 'res.partner'

    customer_type = fields.Selection([
        ('p','person'),('c','company'),
    ])
error
 File "/home/omar/tutorials/odoo10/odoo/fields.py", line 1944, in convert_to_cache
    raise ValueError("Wrong value for %s: %r" % (self, value))
ValueError: Wrong value for shop.customers.commercial_partner_id: shop.customers(<odoo.models.NewId object at 0x7f45b1862950>,)