What is the problem?

I am seeing some weird behaviour when tagging an article with AfD.

Including:

1. In some cases, the {{afd}} template is added twice to the page (see T230455#5661483 and T230455#5673920). See https://test.wikipedia.org/wiki/Dsjfklsdjl. Looking in the revision history, it looks like the same edit is being made twice.
2. In others, when the page has previously been tagged AfD, the subsequent nominations functionality (implemented T231357) does not work. See https://test.wikipedia.org/wiki/Drwpb_New_Page_1.
3. The subsequent nomination feature fails to create the Wikipedia:Articles_for_deletion/$article_(nth_nomination). See the top AfD nomination here: https://test.wikipedia.org/wiki/Drwpb_New_Page_1.
4. I don't think the AfD tag is being logged. See https://en.wikipedia.org/wiki/Special:Log?type=pagetriage-curation&user=&page=Zalki, the article Zalki has been marked AfD. It was working previously, example.

I also often see error popups when tagging AfD, including "Failed to notify author", "Failed to apply tag" and "Failed to find target spot for discussion".

Steps to reproduce problem

1. Go to Special:NewPageFeed and click on a page
2. Click the bin/delete icon, click "Articles for Deletion"
3. Fill in the text input, click "Add Details", click "Mark for Deletion"

Expected behavior:

• An AfD tag should be added to the page once.
  • If it is a subsequent nomination, the tag should be numbered appropriately.
• An entry should be made in Wikipedia:Articles_for_deletion/Log/$today's_date
• A new page should be created Wikipedia:Articles_for_deletion/$article_title
  • Or, for subsequent nominations, Wikipedia:Articles_for_deletion/$article_title_(nth_Nomination)
• Some sort of message should appear on the User_talk of the creator of the page
• There should be an entry recording the AfD tag in Special:Log?type=pagetriage-curation (e.g. marked $article_title for deletion with afd tag)

Observed behavior: See problems listed above.

Environment

Browser: Firefox 68
Wiki(s): Last reproduced: https://test.wikipedia.org MediaWiki 1.35.0-wmf.8 (rMWf20930f9c7d3) 18:32, 26 November 2019; PageTriage 0.3.0 (fec0b93) 08:24, 18 November 2019