ensure initialization of footprints

we need to initialize the footprints before we can call them, accomplish this by calling the initialization function from the metrics tab once the app config is loaded

www/js/metrics/MetricsTab.tsx

@@ -17,6 +17,8 @@ import DailyActiveMinutesCard from './DailyActiveMinutesCard';
 import CarbonTextCard from './CarbonTextCard';
 import ActiveMinutesTableCard from './ActiveMinutesTableCard';
 import { getAggregateData, getMetrics } from '../commHelper';
+import useAppConfig from '../useAppConfig';
+import { initCustomDatasetHelper } from './CustomMetricsHelper';
 
 export const METRIC_LIST = ['duration', 'mean_speed', 'count', 'distance'] as const;
 
@@ -41,6 +43,7 @@ function getLastTwoWeeksDtRange() {
 
 const MetricsTab = () => {
   const { t } = useTranslation();
+  const appConfig = useAppConfig();
   const { getFormattedSpeed, speedSuffix, getFormattedDistance, distanceSuffix } =
     useImperialConfig();
 
@@ -53,6 +56,12 @@ const MetricsTab = () => {
     loadMetricsForPopulation('aggregate', dateRange);
   }, [dateRange]);
 
+  //initialize once config is populated
+  useEffect(() => {
+    if (!appConfig) return;
+    initCustomDatasetHelper(appConfig);
+  }, [appConfig]);
+
   async function loadMetricsForPopulation(population: 'user' | 'aggregate', dateRange: DateTime[]) {
     const serverResponse = await fetchMetricsFromServer(population, dateRange);
     console.debug('Got metrics = ', serverResponse);