When using the indexing operator on a LocalizedString to set a new value for a local variable, I’d expect it to behave the same as a Dictionary<T> instead of throwing an ArgumentException.
Eg.
// If "VariableName" already existed, it should be replaced silently
_locString["VariableName"] = someOtherLocString;
// But this should throw, this `Dictionary<T>`'s .Add() API only allows adding new keys
_locString.Add("VariableName", someOtherLocString);
For now I’m just removing the key before re-adding to change its value, eg.