Modifying the FilterFunctionDefinition asset may make the UIBuilder/stylesheet offsync

Steps to reproduce:

1. Create a new filter function definition asset with parameters
2. In UIBuilder, make a style using that filter
3. Remove the parameters from the asset OR delete the FilterFunctionDefinition
4. Go back to the builder

Actual results: The builder throws exceptions while reading the stylesheet

Expected results: The builder shouldn't complain

Reproducible with versions: 6000.4 6000.3

Not reproducible with versions: 

Can’t test with versions: 

Tested on (OS): 

Notes:

• Also, removing the FilterFunctionDefinition asset reference from a custom filter in UIBuilder is currently spewing exceptions. https://unity.slack.com/archives/G0151D09F99/p1761882618449389