Indigo getLayeredCode freezes with specific molecule

Indigo getLayeredCode(indigo_inchi) freezes when trying to calculate inchi from next molecule

```
CC1OC(OC2C(OS(O)(=O)=O)C(O)C(CO)OC2OC2C(OS(O)(=O)=O)C(C)OC(OC3C(OS(O)(=O)=O)C(C)OC(OCC4OC(OC5C(OS(O)(=O)=O)C(OC(C)C5OS(O)(=O)=O)OCC5OC(OC6C(OS(O)(=O)=O)C(C)OC(OC7C(OS(O)(=O)=O)C(OC(COS(O)(=O)=O)C7O)OC7C(OS(O)(=O)=O)C(OC(=O)/C=C/CCCCCCCCCCCCC)C(OS(O)(=O)=O)C(O)C7O)C6O)C(O)C(OS(O)(=O)=O)C5OS(O)(=O)=O)C(OC(=O)CC(O)CCCCCCCCCCCCCCC)C(OS(O)(=O)=O)C4OS(O)(=O)=O)C3O)C2O)C(OC2OCC(OS(O)(=O)=O)C(OS(O)(=O)=O)C2O)C(OC2OC(COC(=O)/C=C/CCCCCCCCCCCCC)C(OS(O)(=O)=O)C(OS(O)(=O)=O)C2OC(=O)/C=C/CCCCCCCCCCCCC)C1OS(O)(=O)=O
```

Start by reproducing the freeze through getLayeredCode(indigo_inchi) with the molecule supplied in the issue, then trace the InChI calculation entry point and the layered-code path. Done means this input completes without freezing and returns the expected layered code; add a regression test for the reported molecule if the relevant test location is found.

Written by the indexing model from the issue text.