pub fn to_package_set<'g>(
        &self,
        graph: &'g PackageGraph,
        error_message: impl Into<String>,
    ) -> Result<PackageSet<'g>, Error> {
        let error_message = error_message.into();
        let (package_set, matcher) = self.to_package_set_impl(graph, |_| None, &error_message)?;
        matcher.finish(graph, error_message)?;
        Ok(package_set)
    }
Converts this `PackageSetSummary` to a [`PackageSet`].

Returns an error if any of the elements weren't matched.
guppy/src/graph/summaries/package_set.rs