[FIX] web_editor: crash in date formatting if no langage set

This issue was introduced with commit 251b880de1caeeef1f27447d4ad69e1abeffde19 : in case current user has no langage,
we should have a fallback case by retrieving the first langage installed in the database.

closes odoo/odoo#46487

X-original-commit: 67cf1150507b8092c32bf745e4c8620409fdc238
Signed-off-by: Alex Tuyls <alt-odoo@users.noreply.github.com>

addons/web_editor/models/ir_qweb.py

@@ -32,6 +32,7 @@ import odoo.modules
 from odoo import api, models, fields
 from odoo.tools import ustr, posix_to_ldml, pycompat
 from odoo.tools import html_escape as escape
+from odoo.tools.misc import get_lang
 from odoo.addons.base.models import ir_qweb
 
 REMOTE_CONNECTION_TIMEOUT = 2.5
@@ -211,7 +212,7 @@ class Date(models.AbstractModel):
                 attrs['data-oe-type'] = 'datetime'
                 return attrs
 
-            lg = self.env['res.lang']._lang_get(self.env.user.lang)
+            lg = self.env['res.lang']._lang_get(self.env.user.lang) or get_lang(self.env)
             locale = babel.Locale.parse(lg.code)
             babel_format = value_format = posix_to_ldml(lg.date_format, locale=locale)
 
@@ -228,7 +229,7 @@ class Date(models.AbstractModel):
         if not value:
             return False
 
-        lg = self.env['res.lang']._lang_get(self.env.user.lang)
+        lg = self.env['res.lang']._lang_get(self.env.user.lang) or get_lang(self.env)
         date = datetime.strptime(value, lg.date_format)
         return fields.Date.to_string(date)
 
@@ -245,7 +246,7 @@ class DateTime(models.AbstractModel):
         if options.get('inherit_branding'):
             value = record[field_name]
 
-            lg = self.env['res.lang']._lang_get(self.env.user.lang)
+            lg = self.env['res.lang']._lang_get(self.env.user.lang) or get_lang(self.env)
             locale = babel.Locale.parse(lg.code)
             babel_format = value_format = posix_to_ldml('%s %s' % (lg.date_format, lg.time_format), locale=locale)
             tz = record.env.context.get('tz') or self.env.user.tz
@@ -271,7 +272,7 @@ class DateTime(models.AbstractModel):
             return False
 
         # parse from string to datetime
-        lg = self.env['res.lang']._lang_get(self.env.user.lang)
+        lg = self.env['res.lang']._lang_get(self.env.user.lang) or get_lang(self.env)
         dt = datetime.strptime(value, '%s %s' % (lg.date_format, lg.time_format))
 
         # convert back from user's timezone to UTC