I have 2 fields of the type Char and i want to join them to one field. I get an Internal Server Error. Can someone tell me what is wring ?

Code:

from odoo import api, fields, models


class Tarief(models.Model):
    _name = 'insurance.tarief'

    name = fields.Char(compute='_compute_name', store="True")
    code = fields.Char(string="Code")
    omschrijving = fields.Char(string="Omschrijving Verrichting")
    soort_tarief = fields.Selection([
        ('particulier tarieven','Particulier Tarieven'),
        ('szf tarieven','SZF Tarieven'),
        ('bzsr','BZSR')
    ],string="Soort Tarief")
    categorie = fields.Many2one("insurance.categorie", string="Categorie")
    tarief = fields.Float(string="Tarief")

@api.depends('code','omschrijving')
def _compute_name(self):
    for record in self:
    record.name = record.code + record.omschrijving