[debugger] do not wrap null result in helper

GitOrigin-RevId: 5c2b170084bdc3c857693f9eb2044b8485ecd3e6

java/debugger/impl/src/com/intellij/debugger/engine/MethodInvokeUtils.kt

@@ -158,13 +158,13 @@ internal fun tryInvokeWithHelper(
       value = value.getValue(0)
       if (value is ObjectReference) {
         evaluationContext.suspendContext.keepAsync(value)
-      }
-      // clear the reference
-      if (DebuggerUtilsAsync.isAsyncEnabled() && wrapper is ArrayReferenceImpl) {
-        wrapper.setFirstElementToNull()
-      }
-      else {
-        wrapper.setValue(0, null)
+        // clear the reference
+        if (DebuggerUtilsAsync.isAsyncEnabled() && wrapper is ArrayReferenceImpl) {
+          wrapper.setFirstElementToNull()
+        }
+        else {
+          wrapper.setValue(0, null)
+        }
       }
     }
     return InvocationResult(true, value)

java/java-runtime/src/com/intellij/rt/debugger/MethodInvoker.java

@@ -235,6 +235,9 @@ public final class MethodInvoker {
   }
 
   private static Object keepReference(Object ref, boolean soft) {
+    if (ref == null) {
+      return ref;
+    }
     List<Object> objects = keptValues.get();
     if (objects == null) {
       objects = new LinkedList<>();