BUG #16741: Error: subplan "SubPlan 1" was not initialized

The following bug has been logged on the website:

Bug reference: 16741
Logged by: Radek Salač
Email address: radek(at)salac(dot)org
PostgreSQL version: 13.1
Operating system: Debian
Description:

When running the query (whole script can be found here:
https://drive.google.com/file/d/1DaAZaAXVYm-Uo0mb7vxPEi6Ns5_NGd7s/view?usp=sharing)

SELECT
1
FROM tmp_rs_cp "cp"
LEFT JOIN tmp_rs_cfi ON cp.id = tmp_rs_cfi.cp_id
INNER JOIN tmp_rs_cpb "cpb" ON true

ORDER BY (
SELECT 1
FROM tmp_rs_cpis
WHERE cp.id = tmp_rs_cpis.contract_part_id
) ASC LIMIT 10;

I'm getting error:

ERROR: subplan "SubPlan 1" was not initialized
CONTEXT: parallel worker

In PG 13.0 it failed without meaningfull error so we updated but it's still
not working

The explain plan in my case is (JSON format):

[
{
"Plan": {
"Node Type": "Limit",
"Parallel Aware": false,
"Startup Cost": 2100.44,
"Total Cost": 2431.82,
"Plan Rows": 10,
"Plan Width": 8,
"Output": ["1", "((SubPlan 1))"],
"Plans": [
{
"Node Type": "Nested Loop",
"Parent Relationship": "Outer",
"Parallel Aware": false,
"Join Type": "Inner",
"Startup Cost": 2100.44,
"Total Cost": 1690024934.78,
"Plan Rows": 51000000,
"Plan Width": 8,
"Output": ["1", "(SubPlan 1)"],
"Inner Unique": false,
"Plans": [
{
"Node Type": "Nested Loop",
"Parent Relationship": "Outer",
"Parallel Aware": false,
"Join Type": "Left",
"Startup Cost": 2100.44,
"Total Cost": 12392.90,
"Plan Rows": 20000,
"Plan Width": 16,
"Output": ["cp.id"],
"Inner Unique": false,
"Plans": [
{
"Node Type": "Gather Merge",
"Parent Relationship": "Outer",
"Parallel Aware": false,
"Startup Cost": 2100.29,
"Total Cost": 4379.70,
"Plan Rows": 20000,
"Plan Width": 16,
"Output": ["cp.id"],
"Workers Planned": 1,
"Plans": [
{
"Node Type": "Sort",
"Parent Relationship": "Outer",
"Parallel Aware": false,
"Startup Cost": 1100.28,
"Total Cost": 1129.69,
"Plan Rows": 11765,
"Plan Width": 16,
"Output": ["cp.id", "((SubPlan 1))"],
"Sort Key": ["((SubPlan 1))"],
"Plans": [
{
"Node Type": "Index Only Scan",
"Parent Relationship": "Outer",
"Parallel Aware": true,
"Scan Direction": "Forward",
"Index Name": "tmp_rs_cp_id_idx",
"Relation Name": "tmp_rs_cp",
"Schema": "public",
"Alias": "cp",
"Startup Cost": 0.29,
"Total Cost": 304.83,
"Plan Rows": 11765,
"Plan Width": 16,
"Output": ["cp.id", "(SubPlan 1)"],
"Plans": [
{
"Node Type": "Seq Scan",
"Parent Relationship": "SubPlan",
"Subplan Name": "SubPlan 1",
"Parallel Aware": false,
"Relation Name": "tmp_rs_cpis",
"Schema": "public",
"Alias": "tmp_rs_cpis",
"Startup Cost": 0.00,
"Total Cost": 33.12,
"Plan Rows": 9,
"Plan Width": 4,
"Output": ["1"],
"Filter": "(cp.id =
tmp_rs_cpis.contract_part_id)"
}
]
}
]
}
]
},
{
"Node Type": "Index Only Scan",
"Parent Relationship": "Inner",
"Parallel Aware": false,
"Scan Direction": "Forward",
"Index Name": "tmp_rs_cfi_cp_id_idx",
"Relation Name": "tmp_rs_cfi",
"Schema": "public",
"Alias": "tmp_rs_cfi",
"Startup Cost": 0.15,
"Total Cost": 0.31,
"Plan Rows": 9,
"Plan Width": 16,
"Output": ["tmp_rs_cfi.cp_id"],
"Index Cond": "(tmp_rs_cfi.cp_id = cp.id)"
}
]
},
{
"Node Type": "Materialize",
"Parent Relationship": "Inner",
"Parallel Aware": false,
"Startup Cost": 0.00,
"Total Cost": 48.25,
"Plan Rows": 2550,
"Plan Width": 0,
"Plans": [
{
"Node Type": "Seq Scan",
"Parent Relationship": "Outer",
"Parallel Aware": false,
"Relation Name": "tmp_rs_cpb",
"Schema": "public",
"Alias": "cpb",
"Startup Cost": 0.00,
"Total Cost": 35.50,
"Plan Rows": 2550,
"Plan Width": 0
}
]
}
]
}
]
}
}
]