title: DatePicker Vuetify error when set null as default value
body: <p>I have form that need datepicker but not required, and I want to set the default value in datepicker as null and want to be clearable also,
  but when the value is null, the date is not show on the datepicker and show error <code>RangeError: Invalid time value</code></p>
  <p>here the code:</p>
  <pre><code>&lt;v-menu
    ref=&quot;menu&quot;
    v-model=&quot;menuEnd&quot;
    :close-on-content-click=&quot;false&quot;
    transition=&quot;scale-transition&quot;
    offset-y
    min-width=&quot;290px&quot;
  &gt;
    &lt;template v-slot:activator=&quot;{ on }&quot;&gt;
      &lt;v-text-field
        :value=&quot;detail.endDate&quot;
        label=&quot;End Date&quot;
        prepend-icon=&quot;mdi-calendar&quot;
        readonly
        v-on=&quot;on&quot;
        color=&quot;primary&quot;
        clearable
      &gt;&lt;/v-text-field&gt;
    &lt;/template&gt;
    &lt;v-date-picker
      v-model=&quot;detail.endDate&quot;
      @change=&quot;onEndDateChange&quot;
      no-title
      scrollable
      show-current=&quot;false&quot;
    &gt;&lt;/v-date-picker&gt;
  &lt;/v-menu&gt;
  </code></pre>
  <p>data</p>
  <pre><code>data() {
    return {
      menuEnd: false,
      detail: {dateEnd: null},
    }
  },
  methods: {
    onEndDateChange() {
      this.menuEnd = false
    }
  }
  </code></pre>
  <p>the result is here</p>
  <p><a href="https://i.stack.imgur.com/b9Rll.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/b9Rll.png" alt="result" /></a></p>
  <p>Usually I use default value like <code>moment().format('YYYY-MM-DD')</code></p>
  <p>I still working on this one, and maybe anyone can help me.</p>
  <h1>Update</h1>
  <p>on <a href="https://vuetifyjs.com/en/components/date-pickers/#show-sibling-months" rel="nofollow noreferrer">Vuetify Doc</a>, the default value is null, and the date is show, but in my case, date is not showing</p>