I have discovered a bug or glitch in the I.S. Character Pack mod, specifically in both versions, where at some point you are unable to buy more units while playing a multi-day game. It gives the following error:

'Sorry, the mod "I.S. Character Pack (Ship Props)" has failed.
Error: pcall failure in callback function ret=-1
Exception: An attempt was made to access a destroyed object.'

Does anyone know how to fix this, work around it, or why it's happening? I would really appreciate any help

That's a new displayed error message because of a fairly recent Warzone update. The fix is to check that the UI element has not been destroyed yet before attempting to do stuff with it.

I’m not familiar with coding, so does this mean it’s impossible to work around the issue in existing games? Some players have mentioned that they’re still able to purchase units, so I’m wondering if there’s a way to bypass the problem for now

You should ask to Yamada Sergata.

I did, but I am not sure when or if he is going to reply

Might be able to bypass it if you close then reopen the Build menu. Not completely sure though.

I did, but I am not sure when or if he is going to reply

I'm sure they will, just give them some time to look into the issue.