This hides some cases in which no movement is generated

git-svn-id: https://svn.erp5.org/repos/public/erp5/sandbox/amount_generator@37629 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/ExplanationCache.py

@@ -154,7 +154,8 @@ class ExplanationCache:
 
     # path_dict is typically like this:
     #  {'': {'erp5': {'portal_simulation': {'3': {'4': <SimulationMovement at /erp5/portal_simulation/3/4>}}}}}
-    browsePathDict('', path_dict[''])
+    if path_dict:
+      browsePathDict('', path_dict[''])
     self.explanation_path_pattern_cache = result
     return result