fix: Don't oob on nulls in list.get

crates/polars-arrow/src/legacy/kernels/list.rs

@@ -103,9 +103,23 @@ pub fn sublist_get(arr: &ListArray<i64>, index: i64) -> ArrayRef {
 
 /// Check if an index is out of bounds for at least one sublist.
 pub fn index_is_oob(arr: &ListArray<i64>, index: i64) -> bool {
-    arr.offsets()
-        .lengths()
-        .any(|len| index.negative_to_usize(len).is_none())
+    if arr.null_count() == 0 {
+        arr.offsets()
+            .lengths()
+            .any(|len| index.negative_to_usize(len).is_none())
+    } else {
+        arr.offsets()
+            .lengths()
+            .zip(arr.validity().unwrap())
+            .any(|(len, valid)| {
+                if valid {
+                    index.negative_to_usize(len).is_none()
+                } else {
+                    // skip nulls
+                    false
+                }
+            })
+    }
 }
 
 /// Convert a list `[1, 2, 3]` to a list type of `[[1], [2], [3]]`

py-polars/tests/unit/operations/test_gather.py

@@ -48,3 +48,18 @@ def test_list_get_null_offset_17248() -> None:
     assert df.select(
         result=pl.when(pl.col.material.list.len() == 1).then("material").list.get(0),
     )["result"].to_list() == [None, "CI", "CI"]
+
+
+def test_list_get_null_oob_17252() -> None:
+    df = pl.DataFrame(
+        {
+            "name": ["BOB-3", "BOB", None],
+        }
+    )
+
+    split = df.with_columns(pl.col("name").str.split("-"))
+    assert split.with_columns(pl.col("name").list.get(0))["name"].to_list() == [
+        "BOB",
+        "BOB",
+        None,
+    ]