Extensions: Fix DocServer assert failures.

chrome/common/extensions/docs/server2/api_schema_graph.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import json
 import logging
 
 from api_models import GetNodeCategories
 from collections import Iterable, Mapping
 
@@ skipping 62 matching lines @@
     assert len(self._lookup_path) > 1, \
         'Tried to look up parent for the top-level node.'
 
     # lookup_path[-1] is the name of the current node. If this lookup_path
     # describes a regular node, then lookup_path[-2] will be a node category.
     # Otherwise, it's an event callback or a function parameter.
     if self._lookup_path[-2] not in GetNodeCategories():
       if self._lookup_path[-1] == 'callback':
         # This is an event callback, so lookup_path[-2] is the event
         # node name, thus lookup_path[-3] must be 'events'.
-        assert self._lookup_path[-3] == 'events'
+        assert self._lookup_path[-3] == 'events' , \
+            'Invalid lookup path: %s' % (self._lookup_path)
         return self._lookup_path[:-1]
       # This is a function parameter.
       assert self._lookup_path[-2] == 'parameters'
       return self._lookup_path[:-2]
     # This is a regular node, so lookup_path[-2] should
     # be a node category.
     self._AssertIsValidCategory(self._lookup_path[-2])
     return self._lookup_path[:-2]
 
   def _LookupNodeAvailability(self, lookup_path):
@@ skipping 279 matching lines @@
     for path_piece in path:
       node = node.get(path_piece)
       if node is None:
         return LookupResult(found=False, annotation=None)
     return LookupResult(found=True, annotation=node._annotation)
 
   def IsEmpty(self):
     '''Checks for an empty schema graph.
     '''
     return not self._graph