vue-the-mask and element ui input slot 2 value error

[anson-GH]

anyone have the solution for below case ?
<el-input v-model="contactNo" v-mask="'## ### #####'" masked="true" /> // this is valid
I got the error, because v-mask directive requires 1 input, found 2

  <el-input placeholder="enter phone number" v-model="contactNo" class="input-with-select"> 
    <el-select v-model="select" slot="prepend" placeholder="select">
      <el-option label="restaurant phone" value="1"></el-option>
      <el-option label="order phone" value="2"></el-option>
      <el-option label="personal phone" value="3"></el-option>
    </el-select>

Please help