Uncaught TypeError: Cannot read properties of undefined (reading 'customizations')

[kx-cr]

Hello all.

We are experiencing a strange issue where we are using an instance of Bryntum Calendar (as scheduler), which we are customising with Fluent UI components. The page using Bryntum Calendar does not load (for a small number of users) in Chrome browser (varying versions). The problem does not happen in Incognito mode, or in any other browser we have tried. 1 user reports it has always been an issue, 1 or 2 other users are now beginning to see the same case.

It's not really something we can reproduce to show you, and we can't be sure if it's being caused by the calendar, Fluent, react or some combination of all of those based on how we are using them. Strong feeling is that it's Chrome causing it - we have tried fiddling with / removing extensions in case that is having an effect. The error originates in one of the fluent node module files, console error as follows:

Has anybody else experienced something weird like this??

Regards