[FIX] account: fix send invoice mail issue

This commit tries to fix the issue in the "Send Invoice" modal.
Because of this issue, the recipients and body are empty.

task-2032586

closes odoo/odoo#35536

Signed-off-by: oco-odoo <oco-odoo@users.noreply.github.com>

addons/account/wizard/account_invoice_send.py

@@ -51,6 +51,17 @@ class AccountInvoiceSend(models.TransientModel):
             self.composer_id.template_id = self.template_id.id
             self.composer_id.onchange_template_id_wrapper()
 
+    @api.onchange('is_email')
+    def onchange_is_email(self):
+        if self.is_email:
+            if not self.composer_id:
+                res_ids = self._context.get('active_ids')
+                self.composer_id = self.env['mail.compose.message'].create({
+                    'composition_mode': 'comment' if len(res_ids) == 1 else 'mass_mail',
+                    'template_id': self.template_id.id
+                })
+            self.composer_id.onchange_template_id_wrapper()
+
     @api.onchange('is_email')
     def _compute_invoice_without_email(self):
         for wizard in self: