WIP TemplateTool: draft bt5 crashes

product/ERP5/Tool/TemplateTool.py

@@ -141,8 +141,12 @@ class TemplateTool (BaseTool):
           if state == 'installed':
             return bt
           if state == 'not_installed':
+            try:
               last_transition = bt.workflow_history \
                 ['business_template_installation_workflow'][-1]
+            except TypeError:
+              continue
+            else:
               if last_transition['action'] == 'uninstall': # There is not uninstalled state !
                 t = last_transition['time']
                 if last_time < t: