title: Shiny R Date Input Pop Up message
body: <p>I have a server file for an app which gets the stock information from yahoo finance, from a stock symbol which the user inputs. The server code which is relevant here is</p>
  
  <pre><code>dataInput &lt;- reactive({
    getSymbols(input$symb, src = "yahoo", 
      from = input$dates[1],
      to = input$dates[2],
      auto.assign = FALSE)
  })
  </code></pre>
  
  <p>and the ui.r code is</p>
  
  <pre><code>  textInput("symb", "Symbol", "^FTSE"),
  
    dateRangeInput("dates", 
      "Date range",
      start = "2015-01-01", 
      end = as.character(Sys.Date())),
  
    submitButton("Analysis"),width=6)
  </code></pre>
  
  <p>This gives the following</p>
  
  <p><img src="https://i.stack.imgur.com/xJJpv.png" alt="enter image description here"></p>
  
  <p>However if the user inputs a symbol that isn't correct or is not a stock, I get the following error</p>
  
  <pre><code>Error in download.file(paste(yahoo.URL, "s=", Symbols.name, "&amp;a=", from.m,  : 
    cannot open URL 'http://ichart.finance.yahoo.com/table.csv?s=sdf&amp;a=11&amp;b=16&amp;c=2014&amp;d=1&amp;e=25&amp;f=2015&amp;g=d&amp;q=q&amp;y=0&amp;z=sdf&amp;x=.csv'
  </code></pre>
  
  <p>This is good as it cannot open the url seeing as there does not exist a stock for the symbol they inputted. However I want a pop up message to occur saying that there does not exists a stock symbol for the one they have inserted. I have tried out ways to do this, including the bsAlert() approach but I just can't seem to do it. Any help would be great</p>