endog must be strictly positive when using multiplicative error, trend or seasonal components.

Raise code

eject invalid models
        if np.any(self.endog <= 0) and (
            self.error == "mul"
            or self.trend == "mul"
            or self.seasonal == "mul"
        ):
            raise ValueError(
                "endog must be strictly positive when using "
                "multiplicative error, trend or seasonal components."
            )
        if self.damped_trend and not self.has_trend:
            raise ValueError("Can only dampen the trend component")

        # INITIALIZATION METHOD
        # ==