crystal: Fixed missing atomic_sites

Author: Somerandomguy10111

tests/t_labels.py

@@ -1,7 +1,7 @@
 from holytools.devtools import Unittest
 from pymatgen.core import Lattice
 
-from xrdpattern.crystal import CrystalStructure, CrystalBasis
+from xrdpattern.crystal import CrystalStructure
 from xrdpattern.xrd import PowderExperiment, XrayInfo
 from xrdpattern.xrd.experiment import ExperimentTensor
 

xrdpattern/crystal/components/base.py

@@ -41,7 +41,7 @@ def append(self, item : AtomSite):
         self.atom_sites.append(item)
 
     def __add__(self, other : list[AtomSite]):
-        new_base = CrystalBasis()
+        new_base = CrystalBasis(atomic_sites=[])
         for site in self:
             new_base.append(site)
         for site in other: