[Bug] Error: Source "mapbox-dem" cannot be removed while terrain is using it.

Description

This is the code from your example:

  return (
    <>
      <Map
        initialViewState={{
          latitude: 32.6141,
          longitude: -114.34411,
          zoom: 14,
          bearing: 80,
          pitch: 80,
        }}
        maxPitch={85}
        mapStyle="mapbox://styles/mapbox/satellite-v9"
        mapboxAccessToken={env.NEXT_PUBLIC_MAPBOX_ACCESS_TOKEN}
        terrain={{ source: "mapbox-dem", exaggeration: 1.5 }}
      >
        <Source
          id="mapbox-dem"
          type="raster-dem"
          url="mapbox://mapbox.mapbox-terrain-dem-v1"
          tileSize={512}
          maxzoom={14}
        />
      </Map>
    </>
  );

When you add reuseMaps to the Map component, and you navigate to another page (so you unmount Map)

You have this error:

Error: Source "mapbox-dem" cannot be removed while terrain is using it.

I can fix is creating a cleanup composant like :

function MapCleanup() {
  const { current: map } = useMap();

  React.useEffect(() => {
    return () => {
      if (map) {
        try {
          map.getMap().setTerrain(undefined);
        } catch (error) {
          console.warn("Error:", error);
        }
      }
    };
  }, [map]);

  return null;
}

And use it like:

  return (
    <>
      <Map
        reuseMaps
        initialViewState={{
          latitude: 32.6141,
          longitude: -114.34411,
          zoom: 14,
          bearing: 80,
          pitch: 80,
        }}
        maxPitch={85}
        mapStyle="mapbox://styles/mapbox/satellite-v9"
        mapboxAccessToken={env.NEXT_PUBLIC_MAPBOX_ACCESS_TOKEN}
        terrain={{ source: "mapbox-dem", exaggeration: 1.5 }}
      >
        <MapCleanup />
        <Source
          id="mapbox-dem"
          type="raster-dem"
          url="mapbox://mapbox.mapbox-terrain-dem-v1"
          tileSize={512}
          maxzoom={14}
        />
      </Map>
    </>
  );

But its a lot of lines... Would it be possible to add map.getMap().setTerrain(undefined); when reuseMaps unmount mapbox-dem source ?

Expected Behavior

No response

Steps to Reproduce

See my message up

Environment

• Framework version: "react-map-gl": "^8.0.4",
• Map library: "mapbox-gl": "^3.14.0",
• Browser: Chrome 139.0.7258.138
• OS: Ubuntu

Logs

No response

Start by tracing how Map handles reuseMaps unmounting and how the nested Source is removed when terrain references it. Reproduce the example with reuseMaps, terrain, and the mapbox-dem Source, then compare the existing cleanup behavior with the reported MapCleanup workaround. Done means navigating away no longer raises the source-removal error.