Question Localization package "sometimes" throws formatting exception

Hi everyone,
Im having a little trouble here.
The strange thing is code works but sometimes it throws formatting exception. I need to restart application when it starts to throw exceptions. Im assuming that when i set the string reference it tries to parse immediately but there is no giving argument yet and because of that it is throwing the exception. But on the other hand it is working also. It happens sometimes. I couldnt understand why it happens and how i can workaround. I tried to create new LocalizeStringEvent and set its StringReference and arguments but its giving the same result.

Code (CSharp):

1.  
2.     public void SetText(LocalizedString localizedString, object argument)
3.     {
4.         if (lse == null)
5.             lse = GetComponent<LocalizeStringEvent>();
6.  
7.         lse.StringReference = localizedString;
8.         lse.StringReference.Arguments = new[] { argument };
9.     }