Cover null ListView rebuild placeholders

Signed-off-by: Daniel King <dan@spiraldb.com>

Author: danking

vortex-array/src/arrays/listview/rebuild.rs

@@ -544,6 +544,44 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn test_rebuild_flatten_null_row_ignores_invalid_range_payload() -> VortexResult<()> {
+        let elements = PrimitiveArray::from_iter(vec![1i32, 2, 3]).into_array();
+        let offsets = PrimitiveArray::from_iter(vec![0u32, 999, 2]).into_array();
+        let sizes = PrimitiveArray::from_iter(vec![2u32, 999, 1]).into_array();
+        let validity = Validity::from_iter([true, false, true]);
+
+        // SAFETY: this intentionally models a null row whose physical offset and size payloads are
+        // invalid. Rebuild must ignore those payloads and only emit safe placeholder ranges for the
+        // null row.
+        let listview = unsafe { ListViewArray::new_unchecked(elements, offsets, sizes, validity) };
+
+        let mut ctx = SESSION.create_execution_ctx();
+        let flattened = listview.rebuild(ListViewRebuildMode::MakeZeroCopyToList, &mut ctx)?;
+
+        assert_eq!(flattened.offset_at(0), 0);
+        assert_eq!(flattened.size_at(0), 2);
+        assert_eq!(flattened.offset_at(1), 2);
+        assert_eq!(flattened.size_at(1), 0);
+        assert_eq!(flattened.offset_at(2), 2);
+        assert_eq!(flattened.size_at(2), 1);
+        assert!(flattened.validity()?.execute_is_valid(0, &mut ctx)?);
+        assert!(!flattened.validity()?.execute_is_valid(1, &mut ctx)?);
+        assert!(flattened.validity()?.execute_is_valid(2, &mut ctx)?);
+
+        assert_arrays_eq!(
+            flattened.list_elements_at(0)?,
+            PrimitiveArray::from_iter([1i32, 2]),
+            &mut ctx
+        );
+        assert_arrays_eq!(
+            flattened.list_elements_at(2)?,
+            PrimitiveArray::from_iter([3i32]),
+            &mut ctx
+        );
+        Ok(())
+    }
+
     #[test]
     fn test_rebuild_trim_elements_basic() -> VortexResult<()> {
         // Test trimming both leading and trailing unused elements while preserving gaps in the