[2.x] [realtime] Fixed an issue where tag-specified discussion pushing could not work

[edgeinfinity1]

Fixes #0000
I have located this issue long ago, just publishing now because former blomstra/realtime is not open for PRs.

Fixed an issue where tag-specified discussion pushing could not work. The original code tried to index an id from an array of tags which is obviously wrong.

My fix has only been tested and proven work on my own 1.x deployment, please tell me if anything has changed.
There could be something slug-related to reproduce the issue.

Changes proposed in this pull request:

Reviewers should focus on:

See above.

Screenshot

Necessity

• Has the problem that is being solved here been clearly explained?
• If applicable, have various options for solving this problem been considered?
• For core PRs, does this need to be in core, or could it be in an extension?
• Are we willing to maintain this for years / potentially forever?

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Backend changes: tests are green (run composer test).
• Core developer confirmed locally this works as intended.
• Tests have been added, or are not appropriate here.

Required changes:

• Related documentation PR: (Remove if irrelevant)

[imorland]

Thank you for this, we really appreciate your contribution!