skip emailing if user account doesn't exist on idp

Closes #6186

synchro_orleans/data/management/commands/email_new_invoices.py

@@ -93,6 +93,8 @@ class Command(BaseCommand):
             response = requests.get(url)
             try:
                 data = response.json()['data']
+                if not data:
+                    raise ValueError
             except (KeyError, ValueError):
                 continue
             attachment = os.path.join(settings.INVOICES_DIR, 'facture_%s.pdf' % invoice.id)