molecularWeight (and other) calculation fail for thiazolone-like substructures?

some example SMILES where the call fails:
```
C=c2\sc3nc4ccccc4n3c2=O
C=c2sc(=C)nc2=O
C1=CN=c2s/c(=C/c)c(=O)n2C1
COc1cc(C=c2sc3nc4ccccc4n3c2=O)cc(Cl)c1OS(=O)(=O)c1ccccc1
```

```
import indigo

ind = indigo.Indigo()
imol = ind.loadMolecule('COc1cc(C=c2sc3nc4ccccc4n3c2=O)cc(Cl)c1OS(=O)(=O)c1ccccc1')
imol.molecularWeight()
---------------------------------------------------------------------------
IndigoException Traceback (most recent call last)
IndigoException: element: can not calculate implicit hydrogens on aromatic S, charge 0, degree 2, 0 radical electrons
```

dearomatize fails as well:
```
In [27]: imol.dearomatize()
Out[27]: 0
```

Indigo version:
1.7.4.0-g86f1ef175-x86_64-linux-gnu-11.2.1