Fix exception raising in prepare_atom_data
Fix exception raising in prepare_atom_data

Changed behavior to raise a custom exception instead of a generic one.
This is done to better reflect the error.

Related Issues: #455 #464
Pull Request #471

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