Simple repro of bash command substitution not short-circuiting as expected.

exitcode.bash

#!/usr/bin/env bash

test1() {
    local output
    output="$(/does/not/exist)"
    echo "${output}"
}

test2() {
    local output
    output="$(/does/not/exist)"
}

test1
echo $? # prints 0

test2
echo $? # prints 127