Troubleshooting and FAQ

Distinguish the empty results

A country/code lookup returns null for an unknown code or name. A singular subdivision-name lookup also returns null for ambiguity; use the plural result or country/level restriction. Valid countries with no subdivisions give an empty list, while unsupported country codes give null. Facts preserve null for unavailable/conflicting source values. A missing optional country field is undefined; a Japanese subdivision name can be null. None of these values asks a host to fabricate data.

Choose the right import

/codes has code checks, not country names. The root has current countries; withdrawn records live in /withdrawn. A fixed country resource exists only for a country with stored subdivisions; use the loader when the code is selected dynamically. Await on-demand calls. Treat rejected module loading as a host asset/bundling issue rather than silently replacing data. The catalogue names supported fixed paths.

Diagnose a card

Use full country/subdivision codes and the native field names. Flag/map assets are optional and can fail independently of country data. Hosts may supply loaders, drawing colors and capital options. Keep area scope and measurement years when presenting facts. Existing Japanese gaps and source disagreements remain explicit review material.