Wrong error message for `Range` traits when excluding low and high

```
class RangeEditorDemo(HasTraits):
float_number = Range(value=0.5, low=0.0, high=1.0,
exclude_low=True, exclude_high=True)
traits_view = View(
Item('float_number', style='simple'),
title='RangeEditor',
resizable=True
)
demo = RangeEditorDemo()
demo.configure_traits()
```
When I am running something like above, especially with `exclude_low=True, exclude_high=True`, the error message on the dialog does not seem correct:

However, the error message for `exclude_low=False, exclude_high=False` seems correct: