'Fail silently for non-callable attribute and dict lookups which
raise an exception with a "silent_variable_failure" attribute'

@setup({'filter-syntax21': '1{{    var.silent_fail_key    }}2'})
def test_filter_syntax21(self):

    output = self.engine.render_to_string('filter-syntax21', {'var': SomeClass()})
    if self.engine.string_if_invalid:
        self.assertEqual(output, '1INVALID2')
    else:
        self.assertEqual(output, '12')
