diff --git a/src/main/java/de/assecutor/tasklisteditor/model/BlockTypeRegistry.java b/src/main/java/de/assecutor/tasklisteditor/model/BlockTypeRegistry.java
index 42f5c73..d738290 100644
--- a/src/main/java/de/assecutor/tasklisteditor/model/BlockTypeRegistry.java
+++ b/src/main/java/de/assecutor/tasklisteditor/model/BlockTypeRegistry.java
@@ -307,7 +307,7 @@ public class BlockTypeRegistry {
     public synchronized int nextCustomTaskType(Collection<Integer> reserved) {
         var occupied = new HashSet<>(reserved);
         types.values().forEach(type -> occupied.add(type.taskType()));
-        int highest = occupied.stream().mapToInt(Integer::intValue).max().orElse(CUSTOM_TYPE_START - 1);
+        int highest = occupied.stream().mapToInt(value -> value.intValue()).max().orElse(CUSTOM_TYPE_START - 1);
         int next = highest < Integer.MAX_VALUE - 1 ? Math.max(CUSTOM_TYPE_START, highest + 1) : CUSTOM_TYPE_START;
         while (occupied.contains(next)) next++;
         return next;
diff --git a/src/main/java/de/assecutor/tasklisteditor/service/CustomTypeValidator.java b/src/main/java/de/assecutor/tasklisteditor/service/CustomTypeValidator.java
index 1337de3..f72edf7 100644
--- a/src/main/java/de/assecutor/tasklisteditor/service/CustomTypeValidator.java
+++ b/src/main/java/de/assecutor/tasklisteditor/service/CustomTypeValidator.java
@@ -48,7 +48,9 @@ public final class CustomTypeValidator {
     }
 
     private static void validateProperties(JsonNode properties, BlockType base) {
-        require(properties != null && properties.isArray(), "properties must be an array");
+        if (properties == null || !properties.isArray()) {
+            throw new IllegalArgumentException("properties must be an array");
+        }
         require(properties.size() == base.properties().size(), "Properties must match the base type");
         Set<String> ids = new HashSet<>();
         for (JsonNode property : properties) {
@@ -65,7 +67,9 @@ public final class CustomTypeValidator {
     }
 
     private static void validateDefault(JsonNode value, PropertyType type) {
-        require(value != null, "defaultValue is required");
+        if (value == null) {
+            throw new IllegalArgumentException("defaultValue is required");
+        }
         // Leere Vorgaben sind erlaubt; die Eingabefelder behandeln sie wie einen leeren Wert.
         if (value.isNull()) {
             return;
@@ -100,15 +104,17 @@ public final class CustomTypeValidator {
 
     private static String text(JsonNode object, String field, boolean allowBlank) {
         JsonNode value = object.get(field);
-        require(value != null && value.isTextual() && (allowBlank || !value.textValue().isBlank()),
-                field + " must be a string" + (allowBlank ? "" : " and not blank"));
+        if (value == null || !value.isTextual() || (!allowBlank && value.textValue().isBlank())) {
+            throw new IllegalArgumentException(field + " must be a string" + (allowBlank ? "" : " and not blank"));
+        }
         return value.textValue();
     }
 
     private static int integer(JsonNode object, String field) {
         JsonNode value = object.get(field);
-        require(value != null && value.isIntegralNumber() && value.canConvertToInt(),
-                field + " must be an integer");
+        if (value == null || !value.isIntegralNumber() || !value.canConvertToInt()) {
+            throw new IllegalArgumentException(field + " must be an integer");
+        }
         return value.intValue();
     }