Calling geometry.close with ret_isc=True and a single radius fails.

[nils-wittemeier]

Describe the bug
Calling geometry.close with ret_isc=True and a single radius fails. Possibly related to #604

Reproducable code

import sisl
g = sisl.Geometry([0.,0.,0.], lattice=sisl.Lattice([[1.,0.,0.],[0.,1.,0.],[0.,0.,1.]], nsc=[3,3,3]))
print('No extra return', geometry.close(0, R=0.5))                # Works fine
print('Return isc', geometry.close(0, R=0.5, ret_isc=True))    # Failes with TypeError

Output

No extra return [ 0  2  4  5  6  8 10 11 12 13 14 15 16 17 19 21 22 23 25]
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[7], line 4
      2 g = sisl.Geometry([0.,0.,0.], lattice=sisl.Lattice([[1.,0.,0.],[0.,1.,0.],[0.,0.,1.]], nsc=[3,3,3]))
      3 print('No extra return', geometry.close(0, R=1.5))
----> 4 print('Return isc', geometry.close(0, R=1.5, ret_isc=True))
      5 print('Return xyz', geometry.close(0, R=1.5, ret_xyz=True))
      6 print('Return xyz', geometry.close(0, R=1.5, ret_rij=True))

File [~/codes/sisl/src/sisl/geometry.py:3823](https://vscode-remote+ssh-002dremote-002bpc-002eicn2.vscode-resource.vscode-cdn.net/home/ICN2/nwittemeier/Projects/2023/tb-bdg-model/~/codes/sisl/src/sisl/geometry.py:3823), in Geometry.close(self, xyz_ia, R, atoms, atoms_xyz, ret_xyz, ret_rij, ret_isc)
   3821         if ret_isc:
   3822             ret[iisc][i] = concatenate((ret[iisc][i], isc_tile(isc, len(x))), axis=0)
-> 3823 elif len(sret[0]) > 0:
   3824     # We can add it to the list (len(R) == 1)
   3825     # We add the atomic offset for the supercell index
   3826     ret[0][0] = concatenate((ret[0][0], sret[0] + na), axis=0)
   3827     if ret_xyz:

TypeError: object of type 'numpy.int32' has no len()

Version details
Run the below code and add to bug-report:

>>> print(sys.version)
3.11.4 | packaged by conda-forge | (main, Jun 10 2023, 18:08:17) [GCC 12.2.0]
>>> print(sisl.__version__)
0.13.1.dev266+g9b1cc673

[zerothi]

Please check if it is fixed now, I believe so, thanks for the bug-report!

[nils-wittemeier]

Yes, works fine now. Thanks, Nick.