Bugfix when creating help threads, no bot-messages

[Zabuzard]

Overview

This is an attempt to fix the current, frequent, bug where help threads are missing the bot explanation messages.

Explanation

They are caused by an exception:

The source of this is most likely that overviewChannel.createThreadChannel(...) is rate limitted and hence executed a few seconds later. At which point the subsequent event.refer(...) crashes with Unknown interaction cause it is past the 3 seconds threshold. The extra messages are then missing, cause they are flatMap'ed right after the failing notifyUser(...):

Solution

The solution introduced in this PR is to simply make the whole interaction deferred. That way, the code has more time to respond, enough to fit in a delayed thread creation - hopefully.

There are also other alternatives available, such as changing the order of the statements or simply not letting the chain collapse on a single failure. But I would like to try out this fix first.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

0.0% Coverage
0.0% Duplication

[illuminator3]

LGTM

[Zabuzard]

Week old, one approval, merging.