Dolt panics when LOAD_FILE receives a numeric argument below a window

[Yibo-Dong]

What happened

Dolt terminates the query with a Go type assertion panic for LOAD_FILE(1).

Environment

Dolt main commit c3b5ce3, dolt version 2.3.0; MySQL 8.0.43 is the oracle.

How to reproduce

Run this SQL in a fresh Dolt repository.

SELECT FIRST_VALUE(LOAD_FILE(1)) OVER () AS actual
FROM (SELECT 1 AS z) q;

Expected result

MySQL returns the ordinary SQL NULL result for the invalid filename.
MySQL returns:

actual
NULL

Actual result

Dolt exits with:

panic: interface conversion: interface {} is int8, not string