Warning: Error in as.data.frame.default: cannot coerce class ‘"naiveBayes"’ to a data.frame

Question

I have a script to run naive bayes sentiment analysis. I success to run the script. However, when I call the script on rshiny. My script has an error "cannot coerce class naive bayes to a data frame". Can someone help me?

    corpus.clean <- twitclean %>%
      tm_map(content_transformer(tolower)) %>% 
      tm_map(removePunctuation) %>%
      tm_map(removeNumbers) %>%
      tm_map(removeWords, stopwords::stopwords("id", source = "stopwords-iso")) %>%
      tm_map(stripWhitespace)
    
    dtm <- DocumentTermMatrix(corpus.clean)
    {
      m <- as.matrix(dtm)
      v <- sort(rowSums(m),decreasing=TRUE)
      d <- data.frame(word = names(v),freq=v)
    }
    dataframe<-data.frame(text=unlist(sapply(corpus.clean, `[`)), stringsAsFactors=FALSE)
    corpus.txt<-dataframe
    
    inspect(dtm[40:50, 10:15])
    
    df.train <- df[1:7500,]
    df.test <- df[7501:10000,]
    
    dtm.train <- dtm[1:7500,]
    dtm.test <- dtm[7501:10000,]
    
    corpus.train <- corpus[1:7500]
    corpus.test <- corpus[7501:10000]
    
    dim(dtm.train)
    
    fivefreq <- findFreqTerms(dtm.train, 10)
    length((fivefreq))
    fivefreq
    ## [1] 12144
    
    # Use only 5 most frequent words (fivefreq) to build the DTM
    
    dtm.train.nb <- DocumentTermMatrix(corpus.train, control=list(dictionary = fivefreq))
    
    dim(dtm.train.nb)
    ## [1]  1500 12144
    
    dtm.test.nb <- DocumentTermMatrix(corpus.test, control=list(dictionary = fivefreq))
    
    dim(dtm.train.nb)
    
    # Function to convert the word frequencies to yes (presence) and no (absence) labels
    convert_count <- function(x) {
      y <- ifelse(x > 0, 1,0)
      y <- factor(y, levels=c(0,1), labels=c("No", "Yes"))
      y
    }
    
    # Apply the convert_count function to get final training and testing DTMs
    trainNB <- apply(dtm.train.nb, 2, convert_count)
    testNB <- apply(dtm.test.nb, 2, convert_count)
    trainNBm <- as.data.frame(as.matrix(trainNB))
    # Train the classifier
    system.time( classifier <-naiveBayes(trainNB, df.train$klasifikasi, laplace = 1) )
    
    # Use the NB classifier we built to make predictions on the test set.
    system.time(pred <- predict(classifier, newdata=testNB) )
    # Use the NB classifier we built to make predictions on the test set.
system.time(pred <- predict(classifier, newdata=testNB) )

# Create a truth table by tabulating the predicted class labels with the actual class labels 
table("Predictions"= pred,  "Actual" = df.test$klasifikasi )

# Prepare the confusion matrix
conf.mat <- confusionMatrix(pred, df.test$klasifikasi)

conf.mat

I think I got an error here, but I didn't find a solution until now.

system.time( classifier <-naiveBayes(trainNB, df.train$klasifikasi, laplace = 1) )

This is my rshiny ui.R

library(shiny)

# Define UI for application that draws a histogram
shinyUI(fluidPage(

    # Application title
    titlePanel("Analysis Sentimen"),

    # Sidebar with a slider input for number of bins
    sidebarLayout(
        sidebarPanel(
        ),
        mainPanel(
            tabsetPanel(type="tab", 
                        tabPanel("Data File", tableOutput("negpos"), tableOutput("table")), 
                        tabPanel("Preprocessing Data",  tableOutput("corpustxt")), 
                        tabPanel("Confusion Matrix", tableOutput("confmat"), tableOutput("confacc")),
                        tabPanel("Hasil Prediksi", tableOutput("testpred")),
                        tabPanel("Plot", plotOutput("plotpred")))
    )
)))

server.R

library(shiny)

source("C:/Documents/latihan.R")
# Define server logic required to draw a histogram
shinyServer(function(input, output) {
    
    output$table <- renderTable({
        df
    })
    
    output$corpustxt <- renderTable({
        corpus.txt()
    })
    
    output$confmat <- renderTable({
        conf.mat
    })
    
    output$negpos <- renderTable({
        table(df$klasifikasi)
        
    output$plotpred <- renderPlot({
        plotpred
    })
    })
})

This is my error

Warning: Error in as.data.frame.default: cannot coerce class ‘"naiveBayes"’ to a data.frame
  81: stop
  80: as.data.frame.default
  78: data.frame
  77: write.table
  72: observeEventHandler [C:\Users\Documents\AnalisisSentimen\AnalisisSentimenApp/server.R#211]
   1: runApp