Fails when `set -u` is used

Describe the Bug

When the bash setting -u is set to fail on usage of undefined variables, the task helper exits after execution.

Expected Behavior

That it doesn't.

Steps to Reproduce

1. Create a task.
2. Use set -euo pipefail.

Environment

• Version: 2.0.0
• Platform: Debian 12

Additional Context

The error doesn't happen when using e.g. set -eo pipefail.

While testing, I noticed that it does not happen when the there is at least one task-output command between the source call and set -euo pipefail, that is:

source bash_task_helper/files/task_helper.sh
echo foo
set -euo pipefail
task-succeed baz

does not work, but

source bash_task_helper/files/task_helper.sh
task-output foo bar
set -euo pipefail
task-succeed baz

works:

{
  "foo": "bar",
  "status": "success",
  "_output": "baz"
}

Start with bash_task_helper/files/task_helper.sh and reproduce the issue using a task with set -euo pipefail, comparing the failing case with one containing task-output between sourcing and the setting. Done means the task helper no longer exits unexpectedly when set -u is enabled, while the existing task-output behavior remains valid.