refactor: remove stale invalid key check in store (#2050)
refactor: remove stale invalid key check in store (#2050)

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.
resin-io/herostratus,resin-io/etcher,resin-io/resin-etcher,resin-io/etcher,resin-io/resin-etcher,resin-io/etcher,resin-io/herostratus,resin-io/etcher,resin-io/etcher