Chem.MolFromSmiles using SmilesParserParams throws exceptions

[greglandrum]

When used from Python the standard behavior of the RDKit molecules parsers is to return None when there's a problem. However if you provide SmilesParserParams the exception makes it to Python:

[16:01:01] Can't kekulize mol.  Unkekulized atoms: 0 1 2


In [19]: Chem.MolFromSmiles('c1cc1',smiles_params)
[16:01:06] Can't kekulize mol.  Unkekulized atoms: 0 1 2

---------------------------------------------------------------------------
KekulizeException                         Traceback (most recent call last)
<ipython-input-19-3599557b90d0> in <module>
----> 1 Chem.MolFromSmiles('c1cc1',smiles_params)

KekulizeException: Can't kekulize mol.  Unkekulized atoms: 0 1 2

This shouldn't happen.

Configuration (please complete the following information):

• RDKit version: master and the current release branch
• OS: all