[Vuejs]-Cannot read property 'name' of undefined in Vuex/Nuxt

If you choose to split your module into different files (for state, mutations, etc.), you should use the default export in each file instead of export const state.

export default () => ({
  templateDetails: {
    name: 'love',
    // ...
  }
})

The syntax you are using in only good if you have a single file for your store module.

See documentation here.