java script error when using flexdashboard + runtime shiny

[kotamine]

Hi I'm getting an error around the section

// Attempt eval() both with and without enclosing in parentheses.
// Note that enclosing coerces a function declaration into
// an expression that eval() can parse
// (otherwise, a SyntaxError is thrown)
function tryEval(code) {
var result = null;
try {
result = eval(code);

---
title: "Minimum example of WordCloud2 in Fexdashboard"
output: 
  flexdashboard::flex_dashboard:
    social: menu
    source_code: embed
runtime: shiny
---

```{r global, include=FALSE}
library(wordcloud2)

Column {.sidebar}

sliderInput('size', 'Size:', value = 0.5, min = 0.1, max=2)

Column

Word Cloud

renderWordcloud2(
  wordcloud2(data = demoFreq, size = input$size)
  )