Fix composite SRF (RETURNS TABLE) to correctly handle array returns

[wenerme]

Summary

Fixes a crash (segfault) and incorrect behavior when a pljs function with RETURNS TABLE or RETURNS SETOF composite returns a JavaScript array of objects.

Three bugs fixed in call_srf_function (src/pljs.c):

1. Used argv[0] instead of ret — The composite case read input arguments instead of the JS return value, causing all column values to be NULL.
2. No array-of-objects handling — Functions returning arrays like [{id:1, name:'a'}, {id:2, name:'b'}] were not iterated; only a single object was processed, leading to segfault.
3. Missing NULL check before pfree(values) — When pljs_jsvalue_to_datums() returns NULL, pfree(NULL) crashes.

Also fixed a minor memory leak: added JS_FreeValue for array elements in the non-composite scalar array case.

Reproduction

-- This crashes PostgreSQL (segfault) on current main:
CREATE FUNCTION test_srf() RETURNS TABLE(id int, name text) AS $$
  return [{id: 1, name: 'Alice'}, {id: 2, name: 'Bob'}];
$$ LANGUAGE pljs;
SELECT * FROM test_srf();

Test plan

• Added 3 regression tests to sql/function.sql and expected/function.out:
  • RETURNS TABLE with array of objects
  • RETURNS TABLE with single object return
  • RETURNS SETOF rec with array return
• All 20 existing regression tests continue to pass
• Added Dockerfile.test for easy build & test: docker build -f Dockerfile.test -t pljs-test . && docker run --rm pljs-test

[JerrySievert]

thanks for the report and the PR!

I was able to reproduce.