Is there a way to define which type of error occured?

The OnLogError is only generated for error messages caused by errors that occur during calls to methods of TestComplete’s program objects. For example, this event is raised when you call Log.Error to post the error message manually, or when an error occurs because of a call to Sys.Process to obtain the process object which currently does not exist in the system. The OnLogError event is not raised for error messages caused by exceptions. Exceptions can occur in the application under test and also can occur due to errors in the script code. For information on how to handle these exceptions, see Handling Exceptions in Scripts.