Código del problema

// template.html
   <div class="error_page">
        <div class="error-top">
        <div class="login">
          <p>
            <img src="/static/logo.png" alt="">
          </p>
          <!-- <h3 class="inner-tittle t-inner">Bienvenido</h3> -->
          <form @submit.prevent="login()">
              <bootstrap-messages :message="$store.state.messages.message"></bootstrap-messages>
              <input type="password" placeholder="Contraseña" v-model="user.pass">
              <div class="submit">
                <input type="submit" value="Entrar" :disabled="error">
              </div>
              <div class="clearfix"></div>

              <div class="new">
                <p>
                  <a href="#" :click.prevent="resetAccount()">
                    Iniciar con otra cuenta
                  </a>
                </p>
                <p>
                  <router-link to="forget">
                    Olvide mi contraseña
                  </router-link>
                </p>
                <div class="clearfix"></div>
              </div>
            </form>
          </div>
        </div>
     </div>
</div>
// script.js
import { mapMutations } from 'vuex'
import Auth from '../../helpers/auth'
import Router from 'vue-router'

export default {
  data () {
    return {
      user: null,
      error: true
    }
  },
  watch: {
    'user.pass': function (val) {
      if (!+val || val.length < 6) {
        this.error = true
      } else {
        this.error = false
      }
    }
  },
  methods: {
    ...mapMutations([
      'showMessage',
      'errorMessage'
    ]),
    login: function () {
      this.showMessage('<i class="fa fa-spin fa-spinner"></i> Autenticando, por favor espere...')
      Auth.login(this.uid, this.pass, this.successRequest, this.errorRequest)
    },
    successRequest: function (response) {
      this.$router.push('/')
    },
    errorRequest: function (error) {
      this.errorMessage(error)
    },
    resetAccount: function () {
      this.$router.push({path: '/welcome'})
      window.localStorage.removeItem('account')
    }
  },
  created: function () {
    this.user = Auth.getAccount()
    this.user.pass = ''
  }
}