title: Vuejs (vuex) error unknown local mutation type
body: <p>I have an error when I type in my input at the register page. The error said:</p>
  
  <pre><code>unknown local mutation type: setRegisterEmail, global type: authentication/setRegisterEmail
  </code></pre>
  
  <p>I've tried many way still can't fix it.</p>
  
  <p>Here is my register.vue:</p>
  
  <pre><code>Import { mapState, mapMutations, mapActions } from 'vuex';
  export default {
    computed: {
      ...mapState('authentication', [
        'registerEmail',
        'registerPassword',
        'registerError',
      ]),
    },
    methods: {
      ...mapMutations('authentication', [
        'setRegisterEmail',
        'setRegisterPassword',
      ]),
      ...mapActions('authentication', [
        'register',
      ]),
    },
  };
  </code></pre>
  
  <p>Here is my autentication.js:</p>
  
  <pre><code>export default {
      namespaced: true,
      state: {
          registerEmail: null,
          registerPassword: null,
          registerError: null,
          token: null,
      },
      mutation: {
          setToken(state, token) {
              state.token = token;
          },
          setRegisterEmail(state, email) {
              state.registerEmail = email;
          },
          setRegisterPassword(state, password) {
              state.registerPassword = password;
          },
      },
  };
  </code></pre>