Lexical jumps

src/gc.c

@@ -308,6 +308,11 @@ static void mark_stack_frame(StackFrame *frame, size_t *restrict limit) {
         mark_object(frame->dynamic_binding.old_value);
         saturating_dec(limit, 2);
         break;
+    case STACK_FRAME_BLOCK:
+        mark_object(frame->block.tag);
+        // leave protecting value up to internal-return-from
+        saturating_dec(limit, 1);
+        break;
     }
 }