Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/roundup/cgi/client.py", line 1881, in renderContext
    result = pt.render(self, None, None, **args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/engine_zopetal.py", line 93, in render
    TALInterpreter.TALInterpreter(self._v_program, self.macros,
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 192, in __call__
    self.interpret(self.program)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 236, in interpret
    handlers[opcode](self, args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 680, in do_useMacro
    self.interpret(macro)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 236, in interpret
    handlers[opcode](self, args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 413, in do_optTag_tal
    self.do_optTag(stuff)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 398, in do_optTag
    return self.no_tag(start, program)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 392, in no_tag
    self.interpret(program)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 236, in interpret
    handlers[opcode](self, args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 644, in do_condition
    self.interpret(block)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 236, in interpret
    handlers[opcode](self, args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 705, in do_defineSlot
    self.interpret(slot)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 236, in interpret
    handlers[opcode](self, args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 644, in do_condition
    self.interpret(block)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 236, in interpret
    handlers[opcode](self, args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 644, in do_condition
    self.interpret(block)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 236, in interpret
    handlers[opcode](self, args)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/TAL/TALInterpreter.py", line 571, in do_insertStructure_tal
    structure = self.engine.evaluateStructure(expr)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/PageTemplates/TALES.py", line 225, in evaluate
    return expression(self)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/PageTemplates/Expressions.py", line 198, in __call__
    return self._eval(econtext)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/PageTemplates/Expressions.py", line 193, in _eval
    return render(ob, econtext.vars)
  File "/usr/lib/python3.8/site-packages/roundup/cgi/PageTemplates/Expressions.py", line 99, in render
    ob = ob()
  File "/usr/lib/python3.8/site-packages/roundup/cgi/templating.py", line 1248, in history
    label = html_escape(label)
  File "/usr/lib/python3.8/site-packages/roundup/anypy/html.py", line 7, in html_escape
    return html_escape_(str, quote=quote)
  File "/usr/lib/python3.8/html/__init__.py", line 19, in escape
    s = s.replace("&", "&") # Must be done first!
AttributeError: 'NoneType' object has no attribute 'replace'