$data1 = SELECT Null AS a, "e,f,g,h" AS b, "x" AS c;
SELECT a,b,c FROM $data1 FLATTEN OPTIONAL BY a;

$data2 = SELECT 12345 AS a, "e,f,g,h" AS b, "x" AS c;
SELECT a,b,c FROM $data2 FLATTEN OPTIONAL BY a;

$pgint4_ty = Typeof(1p);
$data3 = SELECT 12345p AS a, "e,f,g,h" AS b, "x" AS c UNION SELECT Cast(Null as $pgint4_ty) AS a, "should be" AS b, "omitted" AS c;
SELECT a,b,c FROM $data3 FLATTEN OPTIONAL BY a;

$data4 = SELECT [1,2,3] AS a, "e,f,g,h" AS b, "x" AS c;
SELECT a,b,c FROM $data4 FLATTEN OPTIONAL BY a;

$data5 = SELECT {"a": 1,"b": 2} AS a, "e,f,g,h" AS b, "x" AS c;
SELECT a,b,c FROM $data5 FLATTEN OPTIONAL BY a;