[FIX] l10n_de: ensure o is defined in din5008 report

How to reproduce the bug:

- install l10n_de
- in Settings/General Settings/Business Documents, configure document
  layout to DIN 5008
- try to print one of several:
   => timesheet entries
   => direct debit mandates
   => follow-up reports

Bug:

When you use the DIN 5008 report defined in l10n_de, the o variable is
defined which generates an error.

closes odoo/odoo#81505

Opw: 2659703,2699563,2649221
X-original-commit: c6ffe7eb65844dad33db4390ffeeb24d61a36f40
Signed-off-by: William André (wan) <wan@odoo.com>

addons/l10n_din5008/models/__init__.py

@@ -3,3 +3,4 @@
 
 from . import base_document_layout
 from . import account_move
+from . import hr_timesheet

addons/l10n_din5008/models/hr_timesheet.py

@@ -0,0 +1,15 @@
+from odoo import models, fields
+
+class AccountAnalyticLine(models.Model):
+    _inherit = 'account.analytic.line'
+
+    l10n_din5008_template_data = fields.Binary(compute='_compute_l10n_din5008_template_data')
+    l10n_din5008_document_title = fields.Char(compute='_compute_l10n_din5008_document_title')
+
+    def _compute_l10n_din5008_template_data(self):
+        for record in self:
+            record.l10n_din5008_template_data = []
+
+    def _compute_l10n_din5008_document_title(self):
+        for record in self:
+            record.l10n_din5008_document_title = ''

addons/l10n_din5008/report/din5008_report.xml

@@ -100,9 +100,12 @@
                         </tr>
                     </table>
                     <h2>
-                        <span t-if="not o"><t t-esc="company.l10n_din5008_document_title"/></span>
-                        <span t-elif="'l10n_din5008_document_title' in o"><t t-esc="o.l10n_din5008_document_title"/></span>
-                        <span t-else="" t-field="o.name"/>
+                        <span t-if="not o and not docs"><t t-esc="company.l10n_din5008_document_title"/></span>
+                        <span t-else="">
+                            <t t-set="o" t-value="docs[0]" t-if="not o" />
+                            <span t-if="'l10n_din5008_document_title' in o"><t t-esc="o.l10n_din5008_document_title"/></span>
+                            <span t-else="" t-field="o.name"/>
+                        </span>
                     </h2>
                     <t t-out="0"/>
                 </div>