Prevent some errors when getFunction returns None

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@17907 20353a03-c40f-0410-a6d1-a30d3c3de9de

bt5/erp5_base/SkinTemplateItem/portal_skins/erp5_base/Career_getFunction.xml

@@ -72,7 +72,7 @@ function if the function is a node in the function tree (this happens when\n
 function is acquired from the subordination organisation).\n
 \'\'\'\n
 function_value = context.getFunctionValue()\n
-if len(function_value):\n
+if function_value is None or len(function_value):\n
   return None\n
 return context.getFunction()\n
 </string> </value>
@@ -118,10 +118,10 @@ return context.getFunction()\n
                         <value>
                           <tuple>
                             <string>_getattr_</string>
-<string>context</string>
+                            <string>context</string>
                             <string>function_value</string>
-                            <string>len</string>
                             <string>None</string>
+                            <string>len</string>
                           </tuple>
                         </value>
                     </item>

bt5/erp5_base/bt/revision

-234
\ No newline at end of file
+235
\ No newline at end of file