def METHOD_NAME():
    """Regression test for #668.
    Flux uncertainties smaller than or equal to zero (`lc.flux_err <= 0`) will
    trigger an invalid or non-finite matrix.  We expect `RegressionCorrector`
    to detect this and yield a graceful `ValueError`."""
    lc = LightCurve(flux=[5, 10], flux_err=[1, 0])
    with pytest.raises(ValueError):
        RegressionCorrector(lc)
    lc = LightCurve(flux=[5, 10], flux_err=[1, -10])
    with pytest.raises(ValueError):
        RegressionCorrector(lc)