[FIX] im_livechat: fix traceback when clicking on create button

Before this commit:

When trying to create a record in the live chat it shows traceback.
because the record.id is an object but it requires an integer value.

After this commit:

No traceback while clicking on the create button.

Explanation:

Following commit 488e334fc8
`onchange` methods must handle being called on new record.

Task-2347091
opw-2350463

closes odoo/odoo#59462

X-original-commit: 96d0627a966bfa0e71e5350277d306c0e08cc131
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/im_livechat/models/im_livechat_channel.py

@@ -65,12 +65,12 @@ class ImLivechatChannel(models.Model):
         }
         for record in self:
             values["channel_id"] = record.id
-            record.script_external = view._render(values)
+            record.script_external = view._render(values) if record.id else False
 
     def _compute_web_page_link(self):
         base_url = self.env['ir.config_parameter'].sudo().get_param('web.base.url')
         for record in self:
-            record.web_page = "%s/im_livechat/support/%i" % (base_url, record.id)
+            record.web_page = "%s/im_livechat/support/%i" % (base_url, record.id) if record.id else False
 
     @api.depends('channel_ids')
     def _compute_nbr_channel(self):