BUG: Fix TypeError in assert_index_equal when comparing CategoricalIndex with check_categorical=True and exact=False

Author: Aniketsy

pandas/_testing/asserters.py

@@ -322,7 +322,10 @@ def _check_types(left, right, obj: str = "Index") -> None:
     # skip exact index checking when `check_categorical` is False
     elif check_exact and check_categorical:
         if not left.equals(right):
-            mismatch = left._values != right._values
+            try:
+                mismatch = left._values != right._values
+            except TypeError as e:
+                raise AssertionError(f"{obj} cannot be compared due to incompatible categorical types.\n{e}") from e
 
             if not isinstance(mismatch, np.ndarray):
                 mismatch = cast("ExtensionArray", mismatch).fillna(True)