add try/except for error case

envelops/models.py

@@ -196,8 +196,12 @@ class CagetteEnvelops(models.Model):
         else:
             # Get the oldest check envelops, limited by the number of checks
             docs = []
+            try:
                 for item in c_db.dbc.view('index/by_type_not_archive', key='ch', include_docs=True, limit=payment_data['checks_nb']):
                     docs.append(item.doc)
+            except:
+                # Exception raised if no envelop
+                pass
 
             # If only 1 check to save
             if int(payment_data['checks_nb']) == 1: