Traceback (most recent call last):
  File "/usr/share/catfish/catfish/CatfishWindow.py", line 1166, in perform_query
    for filename in self.search_engine.run(keywords, folder, regex=True):
  File "/usr/share/catfish/catfish/CatfishSearchEngine.py", line 121, in run
    for filename in method.run(keywords, path, regex):
  File "/usr/share/catfish/catfish/CatfishSearchEngine.py", line 390, in run
    command = self.assemble_query(keywords, path)
  File "/usr/share/catfish/catfish/CatfishSearchEngine.py", line 430, in assemble_query
    return "locate --regex -i \"%s\"" % string_regex(keywords, path)
  File "/usr/share/catfish/catfish/CatfishSearchEngine.py", line 56, in string_regex
    regex += string
UnboundLocalError: local variable 'string' referenced before assignment