How to solve an error in download when dowloading a tsv file through a shiny app?

[jtadeusfontes]

Hi,
So I have a simple shiny app to download a tsv file with a data set that is itself downloaded from a database. I have only one function, that downloads the dataset and changes and normalizes it along the way, until I have a final one which is the one that is supposed to be downloaded through the app.
The function is this one:

library(seqRFLP)
library(bold)
library(data.table)
library(rentrez)
library(worms)
library(stringr)
library(readr)
library(fingerprint)
library(dplyr)
library(ggplot2)
library(shiny)
library(rsconnect)

grades<-function(groups){
  taxon<-bold_seqspec(taxon=input$taxa, format = "tsv", marker="COI-5P")
  taxon2<-taxon[(!(is.na(taxon$lat)) | taxon$country!="") & (taxon$species_name!=""),]
  taxon2$number<-str_count(taxon2$nucleotides, pattern="[A-Z]")
  taxon3<-taxon2[(taxon2$number>499),]
  taxon3$species_name<-gsub("sp.", "", taxon3$species_name)
  taxon3$species_name<-gsub("sp. nov", "", taxon3$species_name)
  taxon3$species_name<-gsub("cf.", "", taxon3$species_name)
  taxon3$species_name<-gsub("complex.", "", taxon3$species_name)
  taxon3$species_name<-gsub("cmplx.", "", taxon3$species_name)
  taxon3$species_name<-gsub("[1-9]+", "", taxon3$species_name)
  taxon3=subset(taxon3, lengths(gregexpr("\\w+", taxon3$species_name)) > 1)
  taxon4<-wormsbynames(as.character(taxon3$species_name), marine_only=FALSE, ids=TRUE)
  taxon5<-subset(taxon4, taxon4$isMarine=="1" | taxon4$isBrackish=="1")
  taxon6<-subset(taxon3,as.character(taxon3$species_name)%in% as.character(taxon5$name))
  input$taxa=taxon6
}

Then here is the small app:

ui <- fluidPage(
  titlePanel("Downloading Dataframe with specimen + sequence data"),
  textInput(inputId="taxa", 
            label="Enter the name of the taxon:",placeholder="Example: Cetacea"),
  downloadButton("downloadData","Download")
)

server <- function(input, output){
  taxaInput <- reactive({switch(grades(input$taxa))})
  output$downloadData <- downloadHandler(
    filename = function() {
      paste(input$taxa, ".tsv")
    },
    content = function(file) {
      write.csv(taxaInput(), file, row.names = FALSE)
  })
}

shinyApp(ui=ui,server=server)

So when I click "Download" in the app and choose where I want to save the file I receive the following error:</>

Thanks for any response in advance and sorry for the long question