fix handleConfirmDelete issues in SectionEditor

[nucleogenesis]

Summary

Cherry-picks the commit that fixes a regression in section deletion.

An error remained for me re: 'avoiding redundant navigation' but saw no UX issues due to this.

[rtibbles]

Code changes make sense, I will let manual QA have the final word here!

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.17.0rc2.dev0_git.2.ga8f898da.pex
Windows Installer (EXE)	kolibri-0.17.0rc2.dev0+git.2.ga8f898da-windows-setup-unsigned.exe
Debian Package	kolibri_0.17.0rc2.dev0+git.2.ga8f898da-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.17.0rc2.dev0+git.2.ga8f898da.dmg
Android Package (APK)	kolibri-0.17.0rc2.dev0+git.2.ga8f898da-0.1.4-debug.apk
TAR file	kolibri-0.17.0rc2.dev0+git.2.ga8f898da.tar.gz
WHL file	kolibri-0.17.0rc2.dev0+git.2.ga8f898da-py2.py3-none-any.whl

[radinamatic]

All possible quiz sections changes (renaming, reordering, moving questions around, adding more, etc.) combined with the section deletion, were performed and completed without UI errors.

Uncaught (in promise) NavigationDuplicated: Avoided redundant navigation to current location error did appear in the console, but with no apparent user-facing consequences.

[radinamatic]

LGTM! 👏🏽 💯

[rtibbles]

Had a quick conversation with @nucleogenesis about the possible provenance of the problematic navigation, and it seems like it's not hiding anything further.