need to look up the ivar on the new shape..........

Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>

Author: tekknolagi

zjit/src/hir.rs

@@ -2950,6 +2950,8 @@ impl Function {
                             // We're only looking at T_OBJECT so ignore all of the imemo stuff.
                             assert!(recv_type.flags().is_t_object());
                             let next_shape_id = unsafe { rb_class_shape_transition_add_ivar_no_warnings(class, current_shape_id.0, id) };
+                            let ivar_result = unsafe { rb_shape_get_iv_index(next_shape_id, id, &mut ivar_index) };
+                            assert!(ivar_result, "New shape must have the ivar index");
                             // If the VM ran out of shapes, or this class generated too many leaf,
                             // it may be de-optimized into OBJ_TOO_COMPLEX_SHAPE (hash-table).
                             let new_shape_too_complex = unsafe { rb_jit_shape_too_complex_p(next_shape_id) };