Null error in UI + Can't display some backpack Costumes anymore

[AtomixRO]

Describe the bug
I just caught this while checking the console log and also noticed that the Costume blue wings of fairy (ID 20511) doesn't display anymore and used to before I update the browser from June to October 2024

Screenshots (if applicable)

Packet/Client version
20130618

Browser/device info

• Any

[alisonrag]

steps to reproduce?

[AtomixRO]

steps to reproduce?

There is none beside using a version from June and then update to September/October on my packet version.

You can test on https://classicweb.niktoutro.com (incognito mode) you get the adventurer's pack for free.

Note: I can see both the backpack and wings today in incognito and normal mode. Could be due to the quick update the other day so I believe it has been fixed and that's also what my players told me after pointing this matter to them just now.
I'll close this ticket for now.

[AtomixRO]

I'm re-opening it because the same problem happens again and this doesn't make any sense. Something between mid june & now might have caused some problems.

[AtomixRO]

Additional note: The backpack only appears in development mode is enabled, switched off doesn't display these costumes.

I suspect that's also the reason why splendide maps weren't read from my grf either on chaos.
There's been a grf update over the past few months which could be the cause not being able to read files properly.