GetArrayItem returns wrong results (off-by-one index)

[andygrove]

Description

The get_array_item.sql SQL file test reveals incorrect results from the native GetArrayItem implementation.

Expected vs Actual

== Correct Answer ==      == Spark Answer ==
struct<arr[idx]:int>      struct<arr[idx]:int>
[10]                      [10]
[1]                       [10]   <-- wrong
[20]                      [1]
[30]                      [20]
[null]                    [30]
[null]                    [null]

The results are shifted — it appears the first row's value is duplicated and subsequent rows use the previous row's index. This suggests an off-by-one or stale-index bug in the native GetArrayItem evaluation.

Reproduction

Run CometSqlFileTestSuite — the get_array_item.sql test fails with both parquet.enable.dictionary=false and true.