Fix for interstitial elements without known oxidation states (#212)

* Fix for interstitial elements without known oxidation states

* Fix typo in logging message

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: kavanase

pymatgen/analysis/defects/core.py

@@ -711,12 +711,12 @@ def defect_structure(self) -> Structure:
         inter_states = self.site.specie.common_oxidation_states
         if len(inter_states) == 0:
             _logger.warning(
-                "No oxidation states found for %s. "
+                "No oxidation states found for %s "
                 "in ICSD using `oxidation_states` without frequency ranking.",
                 self.site.specie.symbol,
             )
             inter_states = self.site.specie.oxidation_states
-        inter_oxi = max(inter_states, key=abs)
+        inter_oxi = max((*inter_states, 0), key=abs)
         int_specie = Species(self.site.specie.symbol, inter_oxi)
         struct.insert(
             0,