Safari and VoiceOver bug in OS X

Use VoiceOver with Safari in OS X/macOS, don't put anything into the text field and submit via VO + space on the button. An error messages appears and receives focus. Submit again (via VO + space). Now the submit button will be focussed instead of the error message. (With a post instead of a get, the button would be focussed after the first submit.) Bug or feature?