set(key, value) {
        if (!key) throw new Error('localStorageService - set() - key is required');
        if (!value) throw new Error('localStorageService - set() - value is required');

        if (value) {
          try {
            var val = JSON.stringify(value);
            $window.localStorage.setItem(key, val);
          } catch (e) {
            CACHE[key] = value;
          }

          return null;
        } else {
          this.remove(key);
        }
      }
@desc set a value by key
@param {String} key
@param {Object} obj
@return null