predict method on DecisionTreeRegressor panics when tree is not fit #469

pub fn predict(&self, x: &X) -> Result<Y, Failed> {
        self.tree_regressor.as_ref().unwrap().predict(x)
    }

pub fn predict(&self, x: &X) -> Result<Y, Failed> {
        match &self.tree_regressor {
            Some(tree) => tree.predict(x),
            None => Err(Failed::predict(
                "'fit' should be called before calling 'predict'",
            )),
        }
    }