== Steps to reproduce
# Login to english wikipedia
# Visit https://en.m.wikipedia.org/w/index.php?title=Main_Page#/talk/19
# Notice "[object Object] [object Object]" appears instead of readable text
{F29163496}
== Expected results
- Readable text appears
== Actual results
- "[object Object] [object Object]" appears
== Environments observed
- Browser version: Chrome 74.0.3729.157
- OS version: Mojave 10.14.15
- Device model: MacBook Pro
- Device language: en
== QA Steps:
- Go to mobile version on staging - https://reading-web-staging.wmflabs.org/wiki/Main_Page
- Click "Discussion" button on bottom of the page (you have to be logged in)
- There are 2 discussion available, check that when you view those dicussions, no `[object Object]` appears in the TalkOverlay (it was visible on the bottom of the talk overlay)
- Additionally, please smoke tests most important mobile frontend features. The change was done in the templates rendering logic, which is widely used across whole mobile website, thus we should verify that mobile site is still usuable (login/logout/contributions/recent changes/talk/watchlist etc)
== Developer notes
This seems to stem from our removal of Hogan in T220620 (https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/MobileFrontend/+/506337/). A line in our PageGateaway code (used by TalkOverlay) [[ https://github.com/wikimedia/mediawiki-extensions-MobileFrontend/blob/047c883f2550e54ca856d741bef91be3eaac8437/src/mobile.startup/PageGateway.js#L80 | depended on the return type of `.render` to be a string ]]. However, our new code used mediawiki.template.mustache (a wrapper around mustache) whose `.render` method returned a JQuery object instead. It does not affect every talk overlay, but it does affect ones with wikitext that has multiple sections.