PBXBuildFile KeyError "fileRef"

[truebit]

Traceback (most recent call last):
  File "xUnique.py", line 448, in <module>
    main(sys_argv)
  File "xUnique.py", line 436, in main
    xunique.unique_pbxproj()
  File "xUnique.py", line 107, in unique_pbxproj
    self.unique_project()
  File "xUnique.py", line 141, in unique_project
    self.__unique_project(self.root_hex)
  File "xUnique.py", line 322, in __unique_project
    self.__unique_target(project_hex, target_hex)
  File "xUnique.py", line 352, in __unique_target
    self.__unique_build_phase(target_hex, build_phase_hex)
  File "xUnique.py", line 387, in __unique_build_phase
    self.__unique_build_file(build_phase_hex, build_file_hex)
  File "xUnique.py", line 409, in __unique_build_file
    file_ref_hex = current_node['fileRef']
KeyError: u'fileRef'

• project file content:

        39CF4E07AA9BEA74277D01C8607DF1E3 /* (null) in Headers */ = {isa = PBXBuildFile; };
  ...
              39CF4E07AA9BEA74277D01C8607DF1E3 /* (null) in Headers */,