Lat/Lon field widget values plain string

Hi,

Problem/Motivation

I create a geofield field (non required) and used the Lat/Lon widget.
On my entity edit form, I seized the value "foo" for the Latitude and "bar" for the Longitude.
After submission I got the following error:
The website encountered an unexpected error. Please try again later.

Proposed resolution

The error came from the widget plugin during the massageFormValues method.
The comparison on the component value should be, my value is empty or is not numeric.

Remaining tasks

Reviews needed

User interface changes

None

API changes

None