Catch error on metrics loading from Hetzner

lib/logic/common_enum/common_enum.dart

@@ -20,7 +20,22 @@ enum InitializingSteps {
   checkSystemDnsAndDkimSet,
 }
 
-enum Period { hour, day, month }
+enum Period {
+  hour,
+  day,
+  month;
+
+  int get stepPeriodInSeconds {
+    switch (this) {
+      case Period.hour:
+        return 18;
+      case Period.day:
+        return 432;
+      case Period.month:
+        return 6480;
+    }
+  }
+}
 
 enum ServiceTypes {
   mailserver,

lib/logic/cubit/hetzner_metrics/hetzner_metrics_cubit.dart

@@ -39,16 +39,20 @@ class HetznerMetricsCubit extends Cubit<HetznerMetricsState> {
   }
 
   void load(final Period period) async {
+    try {
       final HetznerMetricsLoaded newState = await repository.getMetrics(period);
       timer = Timer(
         Duration(seconds: newState.stepInSeconds.toInt()),
         () => load(newState.period),
       );
-
-    try {
       emit(newState);
     } on StateError {
       print('Tried to emit Hetzner metrics when cubit is closed');
+    } on MetricsLoadException {
+      timer = Timer(
+        Duration(seconds: state.period.stepPeriodInSeconds),
+        () => load(state.period),
+      );
     }
   }
 }

lib/logic/cubit/hetzner_metrics/hetzner_metrics_repository.dart

@@ -4,6 +4,11 @@ import 'package:selfprivacy/logic/models/hetzner_metrics.dart';
 
 import 'package:selfprivacy/logic/cubit/hetzner_metrics/hetzner_metrics_cubit.dart';
 
+class MetricsLoadException implements Exception {
+  MetricsLoadException(this.message);
+  final String message;
+}
+
 class HetznerMetricsRepository {
   Future<HetznerMetricsLoaded> getMetrics(final Period period) async {
     final DateTime end = DateTime.now();
@@ -31,6 +36,10 @@ class HetznerMetricsRepository {
     final cpuMetricsData = results[0]['metrics'];
     final networkMetricsData = results[1]['metrics'];
 
+    if (cpuMetricsData == null || networkMetricsData == null) {
+      throw MetricsLoadException('Metrics data is null');
+    }
+
     return HetznerMetricsLoaded(
       period: period,
       start: start,