When I visit http://en.m.wikipedia.beta.wmflabs.org/wiki/Test_ios_scrolling_2 or http://en.wikipedia.beta.wmflabs.org/wiki/Test_ios_scrolling_2
I see Lua error in package.lua at line 80: module 'Module:Category handler/data' not found.
I cannot edit the page in mobile.
You can't edit that page because it doesn't exist and you don't have permission to create it. The Lua error is a red herring; you only see it because someone somehow broke MediaWiki:Noarticletext on that wiki.
@Jackmcbarn thanks for explaining that mystery! Is there a bug open against the Lua extension to report the template causing the problem so I could have worked that out myself?
Sure but we should make it easier to debug templates or provide a better error message no?
E.g. lua failed on rendering top level template X...
Normally (i.e. if mobile didn't insist on not loading most JS) you can click on the error message to get a popup with a full Lua backtrace.
Then fix it :) https://www.mediawiki.org/wiki/ResourceLoader/Writing_a_MobileFrontend_friendly_ResourceLoader_module
you can click on the error message to get a popup with a full Lua backtrace.
I didn't notice the error message was a link on desktop (as it looked like a red link). I'd suggest making that clearer.