message: refactor: remove stale invalid key check in store
  We remove a piece of code checking whether `_.keys` returns any non-string
  values in its array, but per the Lodash documentation `_.keys` always returns an
  array of strings.
  Change-Type: patch
  Changelog-Entry: Remove stale `invalidKey` check in store.
diff: @@ -458,16 +458,6 @@ const storeReducer = (state = DEFAULT_STATE, action) => {
  })
  }
  - const invalidKey = _.find(_.keys(action.data), (key) => {
  - return !_.isString(key)
  - })
  -
  - if (!_.isNil(invalidKey)) {
  - throw errors.createError({
  - title: `Invalid setting key: ${invalidKey}`
  - })
  - }
  -
  const invalidPair = _.find(_.toPairs(action.data), (pair) => {
  return _.isObject(_.last(pair))
  })
  