Reproduction steps:
1. Open the attached project "PrefabChanges.zip";
2. Open scene1.unity scene;
3. Add the Button prefab to the Canvas;
4. Add an event handler to the Button's OnClick list by clicking "+";
5. Choose the SetActive(uncheck the tick so it is set to false) function and drag the Text object into the slot from Hierarchy;
6. Open the context menu for the Button component in the Inspector;
7. Select the "BUG: Apply Component Changes To Prefab" button;

Expected results: The changes should be applied on the prefab;
Actual results: Editor crashes.

Fixed in 2018.3.0b8