Asbjørn Sloth Tønnesen [off-list ref] writes:

Add a check to verify that the sub-type is "nest", and throw an
exception if no policy could be generated, as a guard to prevent
against generating a bad policy.

This is a trivial patch with no behavioural changes intended.

Signed-off-by: Asbjørn Sloth Tønnesen <redacted>

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>