Ensure years with no data don't show in year selector

compendium-frontend/src/pages/Standards&Policies/Audits.tsx

@@ -10,10 +10,11 @@ import { useData } from "../../helpers/useData";
 import PillTable from "../../components/PillTable";
 
 function AuditsPage(): React.ReactElement {
+    const dataField = 'audits';
+    const validityCheck = (data: Standards) => data[dataField] !== null;
     const { filterSelection, setFilterSelection } = useContext(FilterSelectionContext);
-    const { data, years, nrens } = useData<Standards>('/api/standards-and-policies/standards', setFilterSelection);
+    const { data, years, nrens } = useData<Standards>('/api/standards-and-policies/standards', setFilterSelection, validityCheck);
 
-    const dataField = 'audits';
 
     const selectedData = data.filter(data =>
         filterSelection.selectedYears.includes(data.year) && filterSelection.selectedNrens.includes(data.nren) && data[dataField] !== null

compendium-frontend/src/pages/Standards&Policies/BusinessContinuity.tsx

@@ -10,10 +10,11 @@ import { useData } from "../../helpers/useData";
 import PillTable from "../../components/PillTable";
 
 function BusinessContinuityPage(): React.ReactElement {
+    const dataField = 'business_continuity_plans';
+    const validityCheck = (data: Standards) => data[dataField] !== null;
     const { filterSelection, setFilterSelection } = useContext(FilterSelectionContext);
-    const { data, years, nrens } = useData<Standards>('/api/standards-and-policies/standards', setFilterSelection);
+    const { data, years, nrens } = useData<Standards>('/api/standards-and-policies/standards', setFilterSelection, validityCheck);
 
-    const dataField = 'business_continuity_plans';
 
     const selectedData = data.filter(data =>
         filterSelection.selectedYears.includes(data.year) && filterSelection.selectedNrens.includes(data.nren) && data[dataField] !== null