fix(VDateInput): prevent crash when pressing enter during text input

[babu-ch]

fix #21072

Description

bug1: crash when pressing enter with empty input
bug2: crash when pressing enter with arbitrary text using adapter

Markup:

<template>
  <v-app>
    <v-container>
      <v-date-input label="Date input"></v-date-input>
    </v-container>
  </v-app>
</template>

[ikushum]

This PR is no longer needed since 84746fb does the same thing and was already introduced since 3.1.17
@johnleider Please verify

[babu-ch]

@ikushum
Bug 2 still occurs in the latest version

[johnleider]

@ikushum Bug 2 still occurs in the latest version

What are exact steps to reproduce Bug 2? It looks fine to me.