chore: better exception when list variable is null (#140)

Fixes #107.
TimefoldAI · Jun 28, 2023 · 00ac56a · 00ac56a
1 parent 974531b
commit 00ac56a
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/.../java/ai/timefold/solver/core/impl/domain/variable/descriptor/ListVariableDescriptor.java b/.../java/ai/timefold/solver/core/impl/domain/variable/descriptor/ListVariableDescriptor.java
@@ -95,7 +95,11 @@ public boolean isInitialized(Object entity) {
     }
 
     public List<Object> getListVariable(Object entity) {
-        return (List<Object>) getValue(entity);
+        Object value = getValue(entity);
+        if (value == null) {
+            throw new IllegalStateException("The planning list variable (" + this + ") of entity (" + entity + ") is null.");
+        }
+        return (List<Object>) value;
     }
 
     public Object removeElement(Object entity, int index) {