api.py: fix TraversalError import

wcs/api.py

@@ -25,7 +25,7 @@ import random
 
 from quixote import get_request, get_publisher, get_response
 from quixote.directory import Directory
-from qommon.errors import AccessForbiddenError, QueryError
+from qommon.errors import AccessForbiddenError, QueryError, TraversalError
 
 from wcs.formdef import FormDef
 
@@ -132,7 +132,7 @@ class ApiFormPage(BackofficeFormPage):
         try:
             self.formdef = FormDef.get_by_urlname(component)
         except KeyError:
-            raise errors.TraversalError()
+            raise TraversalError()
 
         api_user = get_user_from_api_query_string()
         if not api_user: