Select usable Flanders theme by default

backend/tests/test_sprint237_flanders_thematic_on_demand.py

@@ -17,6 +17,8 @@ def test_flanders_workspace_exposes_governed_thematic_products_on_demand() -> No
     assert "activeScopeProject?.name === FLANDERS_WORKSPACE_PROJECT_NAME" in workspace
     assert "new Map<DataThemeId, ThematicRasterProductRead>" in workspace
     assert "'Op aanvraag'" in workspace
+    assert "theme.id === 'space_occupation'" in workspace
+    assert "setActiveThemeId(fallbackTheme.id)" in workspace
     assert "thematicProductKey: thematicProduct.key" in workspace
     assert "datasetsApi.listThematicRasterProducts" in product_hook
     assert "datasetsApi.acquireThematicRaster" in selection_hook

frontend/src/components/map/MapWorkspace.tsx

@@ -790,6 +790,40 @@ export function MapWorkspace({
   const onDemandThematicThemeActive = analysisMode === 'current' && Boolean(activeOnDemandThematicProduct)
   const regionalOnDemandThematicThemeActive = regionalScopeSelected && onDemandThematicThemeActive
   const activeThemeAvailable = Boolean(activeThemeDataset) || onDemandThematicThemeActive
+
+  useEffect(() => {
+    if (
+      !flandersScopeSelected
+      || analysisMode !== 'current'
+      || activeThemeAvailable
+      || (onDemandThematicProductMap.size === 0 && !thematicRasterProductsError)
+    ) {
+      return
+    }
+    const fallbackTheme = DATA_THEMES.find((theme) =>
+      theme.id === 'space_occupation'
+      && Boolean(themeDatasetMap[theme.id] || onDemandThematicProductMap.get(theme.id)),
+    ) ?? DATA_THEMES.find((theme) =>
+      Boolean(themeDatasetMap[theme.id] || onDemandThematicProductMap.get(theme.id)),
+    )
+    if (!fallbackTheme) {
+      return
+    }
+    setActiveThemeId(fallbackTheme.id)
+    const fallbackDataset = themeDatasetMap[fallbackTheme.id]
+    if (fallbackDataset) {
+      onOpenDatasetInMap(fallbackDataset)
+    }
+  }, [
+    activeThemeAvailable,
+    analysisMode,
+    flandersScopeSelected,
+    onDemandThematicProductMap,
+    onOpenDatasetInMap,
+    thematicRasterProductsError,
+    themeDatasetMap,
+  ])
+
   const terrainImageOverlays = useMemo(
     () =>
       activeTheme.id === 'elevation' && selectedProjectId