fix: Slack::sendExec always returns true

[dacgray]

Relevance

When testing on Shop API the method sometimes works, sometimes fails for an unknown reason.

Fire and forget should not mean we should ignore errors. We always return true on sendExec, so we hide failed sends.

Proposal

• get $output
• determine pass/fiail
• return bool on success

Specifics

The response looks something like:

[adhocore]

that is by design and cant be fixed fully
we can however at least check immediate failure with non 0 exit