object_lookup error when icon for mime type is not defined

when i try to link to a object and a .docx document is present in the same folder the lookup window shows "An error happened". it seems that there is a problem with rendering the icon in the lookup window.

after adding the line below in Products.Silva-2.2-py2.4.egg/Products/Silva/__init__.py the error was gone:

('application/vnd.openxmlformats-officedocument.wordprocessingml.document', 'file_doc.png'),

precociously i also added these lines:

('application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'file_xls.png'),
('application/vnd.openxmlformats-officedocument.presentationml.presentation', 'file_ppt.png'),

but in my opinion there should be a graceful fallback when the mime type is not known. this seems to work in the edit tab but not in the lookup window.

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2010-08-12T07:04:12 ERROR Zope.SiteErrorLog 1281589452.230.226512039255 https://foo.com/@@object_lookup
Traceback (innermost last):
  Module ZPublisher.Publish, line 119, in publish
  Module ZPublisher.mapply, line 88, in mapply
  Module ZPublisher.Publish, line 42, in call_object
  Module Products.Silva.browser.lookup, line 60, in __call__
  Module Shared.DC.Scripts.Bindings, line 313, in __call__
  Module Shared.DC.Scripts.Bindings, line 350, in _bindAndExec
  Module Products.PageTemplates.PageTemplateFile, line 126, in _exec
  Module Products.PageTemplates.PageTemplate, line 98, in pt_render
  Module zope.pagetemplate.pagetemplate, line 115, in pt_render
   - Warning: Macro expansion failed
   - Warning: exceptions.KeyError: 'macro_vein_navigation'
  Module zope.tal.talinterpreter, line 271, in __call__
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 534, in do_optTag_tal
  Module zope.tal.talinterpreter, line 516, in no_tag
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 891, in do_useMacro
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 949, in do_defineSlot
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 536, in do_optTag_tal
  Module zope.tal.talinterpreter, line 521, in do_optTag
  Module zope.tal.talinterpreter, line 516, in no_tag
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 855, in do_condition
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 824, in do_loop_tal
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 536, in do_optTag_tal
  Module zope.tal.talinterpreter, line 521, in do_optTag
  Module zope.tal.talinterpreter, line 516, in no_tag
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 536, in do_optTag_tal
  Module zope.tal.talinterpreter, line 521, in do_optTag
  Module zope.tal.talinterpreter, line 516, in no_tag
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 534, in do_optTag_tal
  Module zope.tal.talinterpreter, line 516, in no_tag
  Module zope.tal.talinterpreter, line 346, in interpret
  Module zope.tal.talinterpreter, line 745, in do_insertStructure_tal
  Module Products.PageTemplates.Expressions, line 201, in evaluateStructure
  Module zope.tales.tales, line 696, in evaluate
   - URL: object_lookup
   - Line 371, Column 30
   - Expression: <PythonExpr (view.renderIcon(asset))>
   - Names:
      {'container': <Silva Publication instance foo>,
       'context': <Silva Publication instance foo>,
       'default': <object object at 0x2b0008a0e200>,
       'here': <Silva Publication instance foo>,
       'loop': {'asset': <Products.PageTemplates.Expressions.PathIterator object at 0x1eb06190>},
       'nothing': None,
       'options': {'args': ()},
       'repeat': <Products.PageTemplates.Expressions.SafeMapping object at 0x1e8b2b90>,
       'request': <HTTPRequest, URL=https://foo.com/@@object_lookup>,
       'root': <Application at >,
       'template': <ImplicitAcquirerWrapper object at 0x1e52cd50>,
       'traverse_subpath': [],
       'user': <LDAPUser 'bar'>,
       'view': <Products.Five.metaclass.ObjectLookup object at 0x1eaab850>,
       'views': <zope.app.pagetemplate.viewpagetemplatefile.ViewMapper object at 0x1e8c3110>}
  Module zope.tales.pythonexpr, line 59, in __call__
   - __traceback_info__: (view.renderIcon(asset))
  Module <string>, line 0, in ?
  Module Products.Silva.browser.lookup, line 74, in renderIcon
AttributeError: 'module' object has no attribute 'RegistryError'