The global System.ocg should not cause any errors even if Objects.ocd is not loaded. This means that any functions that depend on certain definitions (e.g. FindLocation) will just not be available.
Currently, it opens a small window in the bottom right corner which blocks all player control and is not intuitive how to close. Now it's a message that will automatically disappear after a while (If the player hasn't finished reading, he can just click the goal icon again).