An unrecoverable Verse runtime error occurred

Summary

I am trying to fix an issue with my UI. Basically, when players leave my map and come back, the UI disappears. I tried to use a WeakMap to create a data structure in Verse while am in the testing mode, is there any help

"An unrecoverable Verse runtime error occurred: Verse unrecoverable error: ErrRuntime_WeakMapInvalidKey: Invalid key used to access persistent var weak_map. (Invalid key used to access persistent var weak_map.)

Truncated callstack follows:
task?comeboss$RefreshUI(:agent):Update (Unknown source) (Source: Unknown(0,0, 0,0))

These details are also available in the [Verse Runtime Errors] section of the log.
The current session will not execute any more Verse code and is likely to result in unwanted behaviour. Would you like to terminate it?"

Please select what you are reporting on:

Creative

What Type of Bug are you experiencing?

Verse

Steps to Reproduce

i just want some advice

Expected Result

i want a persistable data in verse and fix this error

Observed Result

understanding this error

Platform(s)

pc