If an effect checks for the "most," "least," or "fewest" of something with a minimum or maximum condition (e.g., "the land with the fewest Towns/Cities (min. 1))," what happens if two conditions are in conflict (e.g., if the land with the fewest Towns/Cities has 0 Towns/Cities)?

If an effect checks for the "most," "least," or "fewest" of something with a minimum or maximum condition (e.g., "the land with the fewest Towns/Cities (min. 1))," what happens if two conditions are in conflict (e.g., if the land with the fewest Towns/Cities has 0 Towns/Cities)?

Nothing happens, since nothing meets both conditions.
If a minimum or maximum limit is given, ignore anything that doesn't meet the min/max condition before ranking what's left. So when checking for "the land with the fewest Towns/Cities (min. 1)," consider only the lands with at least one Town/City before trying to find the fewest Towns/Cities among those lands.