[Aggregate] Properly return `nil` for `STRING_AGG` when called with `null` or 0-length array #325

	name: Go
	on:
	push:
	branches:
	- main
	pull_request:

	env:
	CC: clang
	CXX: clang++
	jobs:
	build:
	name: build
	strategy:
	matrix:
	os: [ "ubuntu-latest", "macos-latest" ]
	go-version: [ "1.19" ]
	runs-on: ${{ matrix.os }}
	steps:
	- name: checkout
	uses: actions/checkout@v4
	- name: setup Go ${{ matrix.go-version }}
	uses: actions/setup-go@v4
	with:
	go-version: ${{ matrix.go-version }}
	cache: true
	- name: build
	run: \|
	make build
	test:
	name: test
	strategy:
	matrix:
	os: [ "ubuntu-latest", "macos-latest" ]
	go-version: [ "1.19" ]
	runs-on: ${{ matrix.os }}
	steps:
	- name: checkout
	uses: actions/checkout@v4
	- name: setup Go ${{ matrix.go-version }}
	uses: actions/setup-go@v4
	with:
	go-version: ${{ matrix.go-version }}
	cache: true
	- name: test
	run: go test -v ./... -count=1
	coverage:
	name: coverage
	runs-on: ubuntu-latest
	steps:
	- name: checkout
	uses: actions/checkout@v4
	- name: setup Go
	uses: actions/setup-go@v4
	with:
	go-version: '1.21'
	cache: true
	- name: measure coverage
	run: \|
	make cover
	- uses: codecov/codecov-action@v3
	with:
	fail_ci_if_error: false
	verbose: true
	lint:
	name: lint
	runs-on: ubuntu-latest
	steps:
	- name: checkout
	uses: actions/checkout@v4
	- name: setup Go
	uses: actions/setup-go@v4
	with:
	go-version: '1.21'
	cache: true
	- name: run linter
	run: \|
	make lint

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