Fix uncaught SectionError when a nomination redirects to a section

[wilfredor]

Problem

FPCBot crashed with an uncaught SectionError, aborting the entire run:

pywikibot.exceptions.SectionError: 'File:A polarized light micrograph of physiological saline crystals.jpg' is not a valid section of Commons:Featured picture candidates/File:A polarized light micrograph of physiological saline crystals.jpg

(reported by FPCBot on the FPC talk page, 6 June 2026).

Root cause

The nomination subpage was a redirect pointing to a section (a malformed #REDIRECT [[Target#Section]]). In _resolve_nomination_subpage_redirect(), subpage.getRedirectTarget() returned a Page that still carried that section fragment: the ignore_section parameter (which by default strips the section from the target) was only added to getRedirectTarget() in pywikibot 9.3. The candidate's page therefore had a section, and the later Page.get() (reached via filtered_content() → was_cancelled() during park) raised the uncaught SectionError.

Fix

A nomination subpage must redirect to a whole page, never to a section. The fix detects a redirect whose resolved target carries a section and treats it as an invalid redirect: it skips the nomination and reports it via ask_for_help(), consistently with how other invalid redirects are already handled. It uses only Page.section(), so it is independent of the pywikibot version.

Testing

• Reproduced the exact SectionError offline (constructing a Page with the section fragment raises it in Page.get(), before any network call).
• Unit-tested _resolve_nomination_subpage_redirect():
  • a redirect pointing to a section is now skipped (return None) and flagged via ask_for_help(), instead of crashing the run;
  • a normal rename redirect (target without a section) still resolves correctly and records the rename.
• python -m py_compile fpc.py passes.