[BUG] safer comparison in deep_equals if np.any(x != y) does not result in boolean

skbase/utils/deep_equals/_deep_equals.py

@@ -503,18 +503,50 @@
     if isinstance(x == y, bool):
         return ret(x == y, f" !=, {x} != {y}")
 
-    # check if numpy is available
-    numpy_available = _softdep_available("numpy")
-    if numpy_available:
-        import numpy as np
-
     # deal with the case where != returns a vector
-    if numpy_available and np.any(x != y) or np.any(_coerce_list(x != y)):
+    if _safe_any_unequal(x, y):
         return ret(False, f" !=, {x} != {y}")
 
     return ret(True, "")
 
 
+def _safe_any_unequal(x, y):
+    """Return whether any of x != y, if != results in iterable, False on exception.
+
+    Written very defensively to avoid exceptions, as exceptions may be raised
+    since any(x != y) or the safer np.any(x != y) may not be boolean,
+    e.g., in pathological cases of nested objects.
+    """
+    try:
+        unequal = x != y
+    except Exception:
+        return False
+
+    # check if numpy is available
+    numpy_available = _softdep_available("numpy")
+
+    if not numpy_available:
+        try:
+            any_un = any(unequal)
+            if isinstance(any_un, bool):
+                return any_un
+            else:
+                return False
+        except Exception:
+            return False
+
+    import numpy as np
+
+    try:
+        any_un = np.any(x != y) or np.any(_coerce_list(x != y))
+        if isinstance(any_un, bool):
+            return any_un
+        else:
+            return False
+    except Exception:
+        return False
+
+
 def _safe_len(x):
     """Return length of x if len(x) does not result in exception, else -1."""
     if hasattr(x, "__len__"):