Add configuration option: ErrorUnsetFields.

[benma]

Allows the user to see if a a struct has not been populated fully.

In my project, I need a one to one mapping between the map and my struct, and need to catch if a struct field has been left in the default state because of a missing key in the original map.

[bsideup]

:+1:

[HavaH123]

+1 for this feature

[tiwalter]

also +1 for this feature