Extracts the TerrainConfig from a basemap definition if it is valid and enabled.
terrain.enabled
terrain.demUrl
The basemap config object from the registry.
The basemap key (for log messages).
The TerrainConfig if valid and enabled, otherwise null.
Extracts the TerrainConfig from a basemap definition if it is valid and enabled.
terrain.enabledis true butterrain.demUrlis missing.