Validate AET arguments before the API key is checked

AET requires a monthly date (the legacy month name is also accepted) within the data-availability window (from 1987-05-01). Invoked by read_tern() via the .tern_datasets registry.

Usage

.validate_aet(dots, dataset_id)

Arguments

dots

Named list of ... args from read_tern().

dataset_id

Raw dataset_id (unused; uniform validator signature).

Value

NULL (invisibly); called for its side effects (errors).