Typescript in vue - Property 'validate' does not exist on type 'Vue | Element | Vue[] | Element[]'. : <p>I created <code>v-form</code> like this</p>

<pre><code>&lt;v-form ref="form" v-model="valid" lazy-validation&gt;
  ...
  &lt;v-btn
     :disabled="!valid"
     @click="submit"
   &gt;
     submit
   &lt;/v-btn&gt;
&lt;/v-form&gt;
</code></pre>

<p>script:</p>

<pre><code>if (this.$refs.form.validate()) // Error is in here
</code></pre>

<p>If i just <code>console.log(this.$ref.form)</code> the validate() function is available. But why this error is coming while building?</p>
