From 89a5d21de2796e4a9e764021c20e2b5044b1b8e9 Mon Sep 17 00:00:00 2001
From: Luro02 <24826124+Luro02@users.noreply.github.com>
Date: Tue, 17 Dec 2024 13:19:31 +0100
Subject: [PATCH] fix crash in `LeakedCollectionCheck`

---
 .../autograder/core/check/oop/LeakedCollectionCheck.java        | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/autograder-core/src/main/java/de/firemage/autograder/core/check/oop/LeakedCollectionCheck.java b/autograder-core/src/main/java/de/firemage/autograder/core/check/oop/LeakedCollectionCheck.java
index 8ca12338..7b27b40b 100644
--- a/autograder-core/src/main/java/de/firemage/autograder/core/check/oop/LeakedCollectionCheck.java
+++ b/autograder-core/src/main/java/de/firemage/autograder/core/check/oop/LeakedCollectionCheck.java
@@ -300,7 +300,7 @@ private void checkCtExecutableReturn(CtExecutable<?> ctExecutable) {
 
         // a lambda like () -> true does not have a body, but an expression which is a return statement
         // this case is handled here
-        if (statements.isEmpty() && ctExecutable instanceof CtLambda<?> ctLambda) {
+        if (statements.isEmpty() && ctExecutable instanceof CtLambda<?> ctLambda && ctLambda.getExpression() != null) {
             statements = List.of(createCtReturn(ctLambda.getExpression().clone()));
         }