gh-89152: Note truth testing exception in stdtypes.rst

Doc/library/stdtypes.rst

@@ -46,7 +46,9 @@ Any object can be tested for truth value, for use in an :keyword:`if` or
 By default, an object is considered true unless its class defines either a
 :meth:`~object.__bool__` method that returns ``False`` or a
 :meth:`~object.__len__` method that
-returns zero, when called with the object. [1]_  Here are most of the built-in
+returns zero, when called with the object. [1]_ If one of the methods raises an
+exception when they are called, the exception is propagated and the object does
+not have a truth value. Here are most of the built-in
 objects considered false:
 
 .. index::