Issue on mobile Safari (not Cordova)

I have a strange issue this morning. One of our production apps is working on desktop, but not on iOS and iPad (in browser, not native). The issue is replicated in the iOS simulator. Running localhost in the simulator (same codebase) is fine, but the deployed version isn’t.

The site is deployed to modulus using their CLI, so I wonder if the problem lies there? Strange it’s just Mobile Safari (and Chrome).

I get two errors in the console (simulator):

TypeError: undefined is not an object (evaluating 'Package["service-configuration"].ServiceConfiguration')

ReferenceError: Can't find variable: Spacebars

Can anyone shed any light on this?

Just in case anyone stumbles across this. We fixed it! It was a package that was specific to touchscreen devices causing the issue. Curiously, removing and re-adding the package cured it! Might have been an issue with load order.