docs: public JsCodeBuilder popOutputVar() {
      outputVars.pop();
      OutputVar top = outputVars.peek();  // null if outputVars is now empty
      if (top != null) {
        currOutputVar = top.name;
        currOutputVarIsInited = top.initialized;
      } else {
        currOutputVar = null;
        currOutputVarIsInited = false;
      }
      return this;
    }