diff --git a/Elwig/Windows/ChartWindow.xaml.cs b/Elwig/Windows/ChartWindow.xaml.cs
index 111db6f..1f2e2ff 100644
--- a/Elwig/Windows/ChartWindow.xaml.cs
+++ b/Elwig/Windows/ChartWindow.xaml.cs
@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
+using System.Text.Json;
 using System.Text.Json.Nodes;
 using System.Threading.Tasks;
 using System.Windows;
@@ -45,9 +46,9 @@ namespace Elwig.Windows {
             AvNr = avnr;
             var v = Context.PaymentVariants.Find(year, avnr);
             Title = $"{v?.Name} - Lese {year} - Elwig";
-            ExemptInputs = new Control[] {
+            ExemptInputs = [
                 GraphList, OechsleInput, PriceInput, FreeZoomInput, GradationLinesInput, TooltipInput
-            };
+            ];
         }
 
         private void Window_Loaded(object sender, RoutedEventArgs evt) {
@@ -60,15 +61,19 @@ namespace Elwig.Windows {
             await RefreshGraphListQuery();
         }
 
-        private async Task RefreshGraphListQuery(bool updateSort = false) {
-            List<PaymentVar> paymentVars = await Context.PaymentVariants.Where(p => p.Year == Year && p.AvNr == AvNr).ToListAsync();
-
-            if (paymentVars.Count != 1) {
-                return;
+        private static JsonObject? ParseData(PaymentVar variant) {
+            try {
+                return JsonNode.Parse(variant.Data)?.AsObject();
+            } catch (JsonException) {
+                return null;
             }
+        }
 
-            PaymentVar paymentVar = paymentVars[0];
-            var data = JsonNode.Parse(paymentVar.Data).AsObject();
+        private async Task RefreshGraphListQuery(bool updateSort = false) {
+            var paymentVar = await Context.PaymentVariants.FindAsync(Year, AvNr);
+            if (paymentVar == null) return;
+            var data = ParseData(paymentVar);
+            if (data == null) return;
 
             var auszahlungsSorten = data["AuszahlungSorten"]?.AsObject();
             if (auszahlungsSorten == null) {
@@ -81,7 +86,7 @@ namespace Elwig.Windows {
                 return;
             }
 
-            List<Graph> GraphsList = new();
+            List<Graph> GraphsList = [];
 
             int i = 1;
             foreach (var graph in Graphs) {
@@ -97,8 +102,8 @@ namespace Elwig.Windows {
             RefreshInputs();
         }
 
-        private String ParseContracts(JsonObject auszahlungsSorten, int num) {
-            List<string> contracts = new();
+        private string ParseContracts(JsonObject auszahlungsSorten, int num) {
+            List<string> contracts = [];
 
             foreach (var sorte in auszahlungsSorten) {
                 if (sorte.Key == "Kurven") continue;
@@ -111,18 +116,14 @@ namespace Elwig.Windows {
                 }
             }
 
-            return string.Join("\n", contracts.ToArray());
+            return string.Join("\n", contracts);
         }
 
         private async Task<bool> RemoveGraph(int num) {
-            List<PaymentVar> paymentVars = await Context.PaymentVariants.Where(p => p.Year == Year && p.AvNr == AvNr).ToListAsync();
-
-            if (paymentVars.Count != 1) {
-                return false;
-            }
-
-            PaymentVar paymentVar = paymentVars[0];
-            var data = JsonNode.Parse(paymentVar.Data).AsObject();
+            var paymentVar = await Context.PaymentVariants.FindAsync(Year, AvNr);
+            if (paymentVar == null) return false;
+            var data = ParseData(paymentVar);
+            if (data == null) return false;
 
             var auszahlungsSorten = data["AuszahlungSorten"]?.AsObject();
             if (auszahlungsSorten == null) {