title: Mutation not updating state
body: <p>I have my mutation committed, but the user state is not updated instead returns null</p>
  
  <p>I recieve data in mutation
  The axios call returns the user, but don't update state</p>
  
  <pre><code>export default new Vuex.Store({
      state: {
          user: null
      },
      getters: {
          getUser: state =&gt; {
              return state.user;
          }
      },
      mutations: {
          setUser(state, user) {
              let url = domain + "user";
              axios
                  .get(url, {
                      params: {
                          uuid: user.uid
                      }
                  })
                  .then(res =&gt; {
                      Vue.set(state, user, res.data)
                        // tried    state.user = res.data
  
                  })
                  .catch(err =&gt; {
                      console.log(err);
                  });
          }
      },
      actions: {
          setUser(context, user) {
              context.commit('setUser', user);
          }
      }
  })
  </code></pre>
  
  <p>What did I do wrong?
  Thankyou for helping</p>