Error in FUN cannot coerce type closure to vector of type character No stack trace available in R

Question

Error in FUN: cannot coerce type 'closure' to vector of type 'character'
  [No stack trace available]

What to do?

I'm new to R. Below is my code - 

library(shiny)
ui <- fluidPage(
  tabsetPanel(
    tabPanel("Plot", plotOutput(plot)),
    tabPanel("ggplot", plotOutput(ggplot))
  )
)

server <- function(input,output) {
  output$plot = renderPlot({ plot(mpg$hwy,mpg$cty,col = colors(length(mpg$hwy))) })
  output$ggplot = renderPlot({ ggplot(mpg, aes(hwy, cty,fill = year)) + geom_point() + theme_bw() })
}

shinyApp(ui = ui,server = server)

Answer 1

You missed out " " for variables in the plotOutput function.

Write as below - 

library(shiny)
ui <- fluidPage(
  tabsetPanel(
    tabPanel("Plot", plotOutput("plot")),
    tabPanel("ggplot", plotOutput("ggplot"))
  )
)

server <- function(input,output) {
  output$plot = renderPlot({ plot(mpg$hwy,mpg$cty,col = colors(length(mpg$hwy))) })
  output$ggplot = renderPlot({ ggplot(mpg, aes(hwy, cty,fill = year)) + geom_point() + theme_bw() })
}

shinyApp(ui = ui,server = server)