Fix master template bug when no form in context

tailbone/templates/master/form.mako

@@ -6,9 +6,11 @@
   <script type="text/javascript">
 
     ## declare extra data needed by form
+    % if form is not Undefined:
         % for key, value in form.json_data.items():
             ${form.component_studly}Data.${key} = ${json.dumps(value)|n}
         % endfor
+    % endif
 
     % if master.deletable and instance_deletable and master.has_perm('delete') and master.delete_confirm == 'simple':
 
@@ -21,7 +23,9 @@
     % endif
   </script>
 
+  % if form is not Undefined:
       ${form.render_included_templates()}
+  % endif
 
 </%def>