The crashing method in question is patchedBundleForClass().

In general, any swizzles performed by Swift should be written as defensively as possible, including not making any assumptions that the nullability annotations can be relied upon. The existing framework methods frequently actually handle null objects passed to nonnull parameters because these APIs were written long before nullability annotations were a thing.

Oops. Thanks for reporting. cc @mikeash

@swift-ci create

Oops indeed. My bad.

Let's not encode any particular behavior for Nil; we can just check for it when deciding whether to do Special Swift Things.

(You can see what era I learned Objective-C in from my use of Nil.)

Agreed. I think the proper solution is just replacing

if (getImageNameFromSwiftClass(objcClass, &imageName)) {

with

if (objcClass != Nil && getImageNameFromSwiftClass(objcClass, &imageName)) {

I think the check should go in getImageNameFromSwiftClass instead. This will also handle the override of class_getImageName, which also fails gracefully on Nil.

For your viewing pleasure: #20608