title: inherits(x, "character") is not TRUE in R programming Shiny App
body: <p>I am creating Shiny App and the purpose is to input text file and using udpipe library need to create wordcloud, annoate etc...</p>
  
  <p>I am getting "inherits(x, "character") is not TRUE" when running the app. The problem comes from "Annotate" Tab as i am trying to return datatable from Server.R file</p>
  
  <p>ui.R code:</p>
  
  <pre><code>shinyUI(
     fluidPage(
  
      ##today's date
       dateInput("date6", "Date:",
                 startview = "decade"),
       ##current time
       h2(textOutput("CurrentTime")),
    # Application title
    titlePanel("UDPipe Text Analysis"),
  
    # Sidebar with a slider input for number of bins 
    sidebarLayout(
      sidebarPanel(
        # Input: for uploading a file ----
        fileInput("file1", "Choose Text File"),
        # Horizontal line ----
        tags$hr(),
  
        ##checkbox input
        checkboxGroupInput("upos",label = h4("Parts Of Speech to Show:"),
                           c("Adjective" = "ADJ",
                             "Propernoun" = "PROPN",
                             "Adverb" = "ADV",
                             "Noun" = "NOUN",
                             "Verb"= "VERB"),
        selected = c("ADJ","NOUN","VERB"),
        width = '100%'
        #choiceNames =
         # list(icon("Adjective"), icon("Adverb")),
        #choiceValues =
          #list("ADJ", "ADV")
        )),
  mainPanel(
    tabsetPanel(type = "tabs",
                tabPanel("Overview",h4(p("Who deveoped this App")),
                         p("This app supports only text files. ", align = "justify"),
                         h4("Pupropse of this app"),
                         h4("what precaution to take")
                ),
                tabPanel("Annotate",dataTableOutput('Annotate'))
  
                )
  
  
  )
  </code></pre>
  
  <p>server.R code</p>
  
  <pre><code>library(shiny)
  
  # Define server logic required to draw a histogram
  shinyServer(function(input, output) {
  
    Dataset &lt;- reactive({
  
  
      if (is.null(input$file)) { return(NULL) } else
      {
  
        Data &lt;- readlines(input$file1)
        Data  =  str_replace_all(Data, "&lt;.*?&gt;", "")
        return(Data)
  
      }
  
    })  
  
  
    output$Annotate &lt;- renderDataTable(
      {
        english_model = udpipe_load_model("./english-ud-2.0-170801.udpipe")
        x &lt;- udpipe_annotate(english_model, x = Dataset)
        return(x)
      }
    )
  
  
    })
  </code></pre>
  
  <p>I am trying to return data table in output$Annotate variable. But its not working properly.</p>