The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "D:\oodo 14\server\odoo\http.py", line 640, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "D:\oodo 14\server\odoo\http.py", line 316, in _handle_exception
    raise exception.with_traceback(None) from new_cause
ValueError: Invalid field 'invoice_seq' on model 'product.product'

my code

from odoo import api, fields, models, _


class SkitVendorInvoice(models.Model):
    _name = "skit.vendor.invoice"
    _description = "Vendor Invoice"

    # vendor_name = fields.Char(string="Name")
    vendor_id = fields.Many2one('res.partner', string="Supplier/Vendor", required=True)
    help_id = fields.Many2one('product.product', string="product")
    invoice_seq = fields.Char(string='Sales Invoice', required=True, copy=False, readonly=True,
                              default=lambda self: _('New'))
    invoice_date = fields.Date(string="Invoice Date")
    amount = fields.Integer(string="Amount")
    product_sale_ids = fields.One2many('product.vendor.invoice', 'product_id', string='product vendors')

    @api.model
    def create(self, values):
        if values.get('invoice_seq', _('New')) == _('New'):
            values['invoice_seq'] = self.env['ir.sequence'].next_by_code('sales.invoice') or _('New')
        res = super(SkitVendorInvoice, self).create(values)
        return res


    class ProductVendorInvoice(models.Model):
        _name = "product.vendor.invoice"
        _description = "Product Vendor Invoice"

        description = fields.Char(string='Description')
        qty = fields.Integer(string='Quantity')
        # product_id = fields.Many2one('skit.vendor.invoice', string='product')
        product_id = fields.Many2one('product.product', string="product")

        um_code = fields.Char(string='UoM Code')
        unit_price = fields.Integer(string='Unit Price')
        sub_total = fields.Integer(string='Sub Total')