[-] FO : Stores : warning thrown if hours is empty

If the "hours" field is empty and you display errors (e.g. when developing), a warning is thrown because of array_filter used on a non-array value. The generated XML gets corrupted because of this error, so the JS parser fails and no store is shown on the FO.
Merge pull request #2213 from axometeam/patch-41

[-] FO : Stores : warning thrown if hours is empty