BUG: pandas-devGH-23236 fix .iat assignment creates new column on type error

Author: RoeiRaz

pandas/core/frame.py

@@ -2716,7 +2716,10 @@ def _set_value(self, index, col, value, takeable=False):
         except (KeyError, TypeError):
 
             # set using a non-recursive method & reset the cache
-            self.loc[index, col] = value
+            if takeable:
+                self.iloc[index, col] = value
+            else:
+                self.loc[index, col] = value
             self._item_cache.pop(col, None)
 
             return self