docs: @Override
    protected SoyValue visitVarRefNode(VarRefNode node) {
  
      // Cannot preevaluate injected data.
      if (node.isInjected()) {
        throw RenderException.create("Cannot preevaluate reference to ijData.");
      }
  
      // Otherwise, super method can handle it.
      SoyValue value = super.visitVarRefNode(node);
  
      if (value instanceof UndefinedData) {
        throw RenderException.create("Encountered undefined reference during preevaluation.");
      }
  
      return value;
    }