Cannot select time without choose the date first

[faizaaulia]

Describe the bug The time cannot be selected it the user doesn't choose the date first

To Reproduce Steps to reproduce the behavior:

1. Go to 'Stackblitz playground](https://stackblitz.com/edit/vuepic-vue-datepicker?file=src%2Fcomponents%2FPlayground.vue)
2. Click the datepicker
3. Click time overlay -> time picker menu opened
4. Click select
5. Unable to select time

Expected behavior User is able to select the time without choose the date first, when the time is selected, the date value will be auto assign to today date

Screenshots Notice that in this picture, user has select a date then then user will be able to select the time When the date is not selected yet, the time is not able to be selected

Desktop & mobile (please complete the following information):

• Browser [e.g. chrome, safari]
• Library version [e.g. 3.0.0]

[Jasenkoo]

Expected behaviour, won't be actioned. Alternating this will cause random behavior in the validation logic. You can simply provide a default date if needed.