我想在Spyder IDE中使用PDE Solver Fipy，并尝试根据官方安装指南进行安装： 现在建议在使用该软件包之前运行fipy.test（），并出现以下错误。

File "C:\Users\Me\AppData\Roaming\Python\Python27\site-packages\fipy\tests\test.py",line 263,in run_tests
    raise exitErr

UnboundLocalError: local variable 'exitErr' referenced before assignment

在这种情况下，我不明白这意味着什么，这是此错误所指的代码：

    try:
        unittest.main(
            None,None,[unittest.__file__]+self.test_args,testLoader = loader_class()
            )
    except SystemExit as exitErr:
        # unittest.main(...,exit=...) not available until Python 2.7
        from fipy.tests.doctestPlus import report_skips
        report_skips()
        if self.timetests is not None:
            pass
        else:
            raise

    if "legacy" in printoptions:
        numerix.set_printoptions(legacy=printoptions["legacy"])

    if self.timetests is not None:
        from fipy.tests.doctestPlus import _DocTestTimes
        import numpy
        _DocTestTimes = numpy.rec.fromrecords(_DocTestTimes,formats='f8,S255',names='time,test')
        _DocTestTimes.sort(order=('time','test'))
        numpy.savetxt(self.timetests,_DocTestTimes[::-1],fmt="%8.4f\t%s")

    raise exitErr