Undid temporary hack introduced by rust-lang#66392.

src/librustc_typeck/astconv.rs

@@ -1409,15 +1409,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         // removing the dummy `Self` type (`trait_object_dummy_self`).
         let trait_ref_to_existential = |trait_ref: ty::TraitRef<'tcx>| {
             if trait_ref.self_ty() != dummy_self {
-                // FIXME: There appears to be a missing filter on top of `expand_trait_aliases`,
-                // which picks up non-supertraits where clauses - but also, the object safety
-                // completely ignores trait aliases, which could be object safety hazards. We
-                // `delay_span_bug` here to avoid an ICE in stable even when the feature is
-                // disabled. (#66420)
-                tcx.sess.delay_span_bug(DUMMY_SP, &format!(
-                    "trait_ref_to_existential called on {:?} with non-dummy Self",
-                    trait_ref,
-                ));
+                bug!("trait_ref_to_existential called on {:?} with non-dummy Self", trait_ref);
             }
             ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref)
         };