Unity how to validate/preprocess variables when they're assigned in the inspector

I have a string animationPaths variable. And I am using the OdinInspector library to drag and drop files into the inspector to get their paths.
I want to preprocess the paths in order to remove the final “.prefab” extensions.

[FilePath(ParentFolder = "Assets/Project/Resources")]
[SerializeField] private string[] animationPaths;

The OnValueChanged callback allows me to process the variables when one is changed. But the callback is not called when a variable is first assigned in the inspector.

Is there any way to preprocess variables the moment they are assigned in the inspector? (Without using the Update function)