message: Add POSITION function null test case in test-suite
diff: @@ -25,6 +25,10 @@ test_case!(position, async move {
  r#"SELECT POSITION("s" IN "cheese") AS test"#,
  Ok(select!(test; I64; 5)),
  ),
  + (
  + r#"SELECT POSITION(NULL IN "cheese") AS test"#,
  + Ok(select_with_null!(test; Null)),
  + ),
  (
  r#"SELECT POSITION(1 IN "cheese") AS test"#,
  Err(EvaluateError::FunctionRequiresStringValue(String::from("POSITION")).into()),
  