Steps to replicate the issue

• Visit https://test.wikipedia.org/wiki/Test80286
• Blank the page
• Go to the PageTriage toolbar and click the trash can
• Click "Proposed deletion" tab
• Select the radio button "Proposed deletion"
• For the textarea, type "Test"
• Click "Mark for deletion"

What happens?:

• PageTriage pops up an error message "Tag subst:prod is missing required parameter"
• PageTriage prepends

{{Proposed deletion/dated
  |concern = 
  |timestamp = 20220715013828
  |help = 
}}

What should have happened instead?:

• PageTriage should display no error message
• PageTriage should prepend

{{Proposed deletion/dated
  |concern = Test
  |timestamp = 20220715013828
  |help = 
}}

Software version

Other information

• This code is throwing the error: https://github.com/wikimedia/mediawiki-extensions-PageTriage/blob/58ef5381d2c1d5455a92090477bd6488544f3bf0/modules/ext.pageTriage.views.toolbar/delete.js#L629-L644
• Looks like tagObj.params[param].value is blank instead of containing the value of the textarea
• Reported by ComplexRational at https://en.wikipedia.org/wiki/Wikipedia_talk:New_pages_patrol/Reviewers#PROD_bug