As discovered in #345 (comment), marshaling is extremely fragile w.r.t. data created or stored outside of the solution.

All auxiliary varinfos (including RETURN and RichVarinfo) should be explicitly marshaled and unmarshaled in analyses that use them.
The reasonable approach would be to extend Spec's init and finalize.

I already started something in https://github.com/goblint/analyzer/tree/spec-marshal.