Handle more Unity expected exceptions
Handle more Unity expected exceptions

* MissingComponentException - thrown by "null" instance objects returned from GetComponent for a Component that isn't attached to the current GameObject. Fixes DEXP-585430
* MissingReferenceException - thrown by destroyed objects. Fixes DEXP-534612
* UnassignedReferenceException - thrown by "null" instance objects in a serialised field that has never been assigned. Fixes DEXP-558487

JetBrains/resharper-unity,JetBrains/resharper-unity,JetBrains/resharper-unity