A SAFE_POINT triggers on color scheme changing in the 3D View

Scenario to reproduce:

1. Open "data/samples/PDB/1CF7.pdb".
2. Call a context menu on the 3d View.
3. Select {Coloring Scheme -> Molecular Chains}

   .
   Current state: color scheme is incorrect, there is an error in the log:

   [ERROR][16:31] Trying to recover from error: Invalid type conversion at src/BioStruct3DColorScheme.cpp:182