diff --git a/store/templates/base.html b/store/templates/base.html
index bc3ef39af00a3c1f8e758c42b0578c4d1d4326b9..edbc7f7b1b63cb4c5ce72f42c72f1e6e5730e8b9 100644
--- a/store/templates/base.html
+++ b/store/templates/base.html
@@ -156,11 +156,11 @@
     {% comment %} Error messages {% endcomment %}
     <script>
         // Shows an error in the alert div.
-        // If there is an error message in the response, use it.
-        // Otherwise use the def.
-        function showError(response, def) {
-            if (response && "error" in response) {
-                displayError(response.error);
+        // Try to extract an error message from error.
+        // Otherwise use def.
+        function showError(error, def) {
+            if (error && "responseJSON" in error && "error" in error.responseJSON) {
+                displayError(error.responseJSON.error);
             } else {
                 displayError(def)
             }
diff --git a/store/templates/buy.html b/store/templates/buy.html
index c56ca61c798dca3f7e21bfe816113c7ada427d8f..9999c1245ad53e49f8872f44252080990dd8570c 100644
--- a/store/templates/buy.html
+++ b/store/templates/buy.html
@@ -127,11 +127,7 @@
 
     function buy(id) {
         error = error => {
-            err = null;
-            if (error && "responseJSON" in error) {
-                err = error.responseJSON
-            }
-            showError(err, "Fehler beim Einkaufen");
+            showError(error, "Fehler beim Einkaufen");
         }
 
         // Check if id is a valid integer
@@ -176,11 +172,7 @@
 
     function revert(id) {
         error = error => {
-            err = null;
-            if (error && "responseJSON" in error) {
-                err = error.responseJSON
-            }
-            showError(err, "Fehler beim R&uuml;ckg&auml;gig machen eines Einkaufes.");
+            showError(error, "Fehler beim R&uuml;ckg&auml;gig machen eines Einkaufes.");
         }
 
         return function() {
diff --git a/store/templates/charge.html b/store/templates/charge.html
index 578d043c8b55d66c2f5abd5ab252e9bb9ef6f2ec..0a0afd1120c70ff5e9746bab47d8962fed5beb4d 100644
--- a/store/templates/charge.html
+++ b/store/templates/charge.html
@@ -111,11 +111,7 @@
 
     function charge() {
         error = error => {
-            err = null;
-            if (error && "responseJSON" in error) {
-                err = error.responseJSON;
-            }
-            showError(err, "Fehler beim Aufladen");
+            showError(error, "Fehler beim Aufladen");
         }
 
         // Get amount from text field
@@ -161,11 +157,7 @@
     // Returns a function that can be called to revert the charge where charge.id == id
     function revert(id) {
         error = error => {
-            err = null;
-            if (error && "responseJSON" in error) {
-                err = error.responseJSON
-            }
-            showError(err, "Fehler beim R&uuml;ckg&auml;gig machen einer Aufladung");
+            showError(error, "Fehler beim R&uuml;ckg&auml;gig machen einer Aufladung");
         };
 
         return function() {
diff --git a/store/templates/transfer.html b/store/templates/transfer.html
index 0f5087660670d9293226ec730af35c03e36a6c72..7cdebe4d6fc8b83e07e139af4a8ef2bb4f3e2ef7 100644
--- a/store/templates/transfer.html
+++ b/store/templates/transfer.html
@@ -175,11 +175,7 @@
 
     function transfer(receiver) {
         error = error => {
-            err = null;
-            if (error && "responseJSON" in error) {
-                err = error.responseJSON;
-            }
-            showError(err, "Fehler beim &Uuml;berweisen");
+            showError(error, "Fehler beim &Uuml;berweisen");
         }
 
 
@@ -242,11 +238,7 @@
     // Returns a function that can be called to revert the transfer where transfer.id == id
     function revert(id) {
         error = error => {
-            err = null;
-            if (error && "responseJSON" in error) {
-                err = error.responseJSON;
-            }
-            showError(err, "Fehler beim R&uuml;ckg&auml;gig machen einer&Uuml;berweisung");
+            showError(error, "Fehler beim R&uuml;ckg&auml;gig machen einer&Uuml;berweisung");
         }
 
         return function() {