Fix convergence handling in run_legacy_simulation
Fix convergence handling in run_legacy_simulation

* now all the accessed values exist
* not guaranteed that the convergence handling is actually sensible

kaushik94/tardis,kaushik94/tardis,Tobychev/tardis,orbitfold/tardis,Tobychev/tardis,Tobychev/tardis,orbitfold/tardis,kaushik94/tardis,orbitfold/tardis,kaushik94/tardis,orbitfold/tardis