How do I creating a flexdashboard from shiny app

Question

I want to have a shiny app where I upload an xlsx file, which will be splitted and prepared. And this splitted and prepared data should be the params for a flexdashboard. But I always get the error that params are not declared in YAML (exact error message see below)

shiny app:

library(shiny)
library(readr)
library(readxl)
library(tidyverse)

ui <- fluidPage(
  titlePanel("File: Kundenstruktur Upload"),
  sidebarLayout(
    sidebarPanel(
      fileInput("file", "Upload Kundenstruktur.xlsx")
    ),
    mainPanel(
      tableOutput("data_table"),
      downloadButton("report", "Generate report")
    )
  )
)

server <- function(input, output, session) {
  
  # get color codes
  uploaded_colors <- reactive({
    req(input$file)
    df <- readxl::read_xlsx(input$file$datapath, sheet = "Gruppen") %>% 
      janitor::clean_names()
    df
  })
  
  # get color codes
  uploaded_data <- reactive({
    req(input$file)
    df <- readxl::read_xlsx(input$file$datapath, sheet = "Stammdaten") %>% 
      janitor::clean_names()
    df
  })
  
  # prep the data
  prep_data <- reactive({
    kunden <- unique(uploaded_data()$kundenname)
    
    kundenstruktur_tbl <- tibble()
    for (i in 1:length(kunden)){
      kunde <- uploaded_data() %>% 
        filter(kundenname == kunden[i])
      
      empfehlungen <- uploaded_data() %>% 
        filter(empfehlung_von == kunde$kundenname)
      
      temp_tbl <- tibble(
        from_name = kunde$kundenname,
        to_name   = empfehlungen$kundenname,
        from_id   = kunde$kunden_id,
        to_id     = empfehlungen$kunden_id,
        from_gruppe = kunde$gruppe,
        to_gruppe   = empfehlungen$gruppe,
        from_verbindung = kunde$verbindung,
        to_verbindung   = empfehlungen$verbindung
      )
      
      kundenstruktur_tbl <- bind_rows(kundenstruktur_tbl, temp_tbl)
    }
    
    kundenstruktur_tbl
  })
  
  # create nodes
  nodes <- reactive({
    uploaded_data() %>%
      select(id = kunden_id, label = kundenname, group = gruppe, verbindung) %>%
      left_join(uploaded_colors(), by = c("group" = "gruppen")) %>%
      mutate(
        shape = "box",
        icon.face = "fontAwesome",
        icon.code = "f0ce",
        icon.size = 50,
        icon.color = farbe
      )
  })
  
  # create nodes
  edges <- reactive({
    prep_data() %>%
      select(from = from_id, to = to_id, from_gruppe) %>%
      left_join(uploaded_colors(), by = c("from_gruppe" = "gruppen")) %>%
      rename(font.color = farbe)
  })
  

  output$report <- downloadHandler(
    # For PDF output, change this to "report.pdf"
    filename = "report.html",
    content = function(file) {
      tempReport <- "KundenNetzwerk_Shiny.Rmd"
      file.copy("report.Rmd", tempReport, overwrite = TRUE)

      # Set up parameters to pass to Rmd document
      params <- list(params = list(nodes = isolate(nodes()), edges = isolate(edges()), data = isolate(prep_data())))

      rmarkdown::render(tempReport, output_file = file,
                        params = params,
                        envir = new.env(parent = globalenv())
      )
    }
  )

  # Display the first few rows of the uploaded data
  output$data_table <- renderTable({
    head(uploaded_data())
  })
  
}

shinyApp(ui = ui, server = server)

flexdashboard:

---
title: "Kundennetzwerk"
output: 
  flexdashboard::flex_dashboard:
    css: css/styles-default.css
    #logo: img/KC.png
params:
  edges: NA
  nodes: NA
  data: NA
  
---


    
```{r include=  FALSE}

library(visNetwork)
library(tidyverse)
library(DT)

```


Sidebar {.sidebar}
============================================================================= 
<br>
<br>
![](img/AFB_AG.png){width=100%}



Kundenstruktur {data-icon="fa-sitemap"}
============================================================================= 


Row {.tabset}
------------------------------------- 

### Netzwerk

```{r}

visNetwork(params$nodes, params$edges, width = "100%") %>%

  visGroups(groupname = "Familie",         color = "#c72237", shape = "ellipse") %>%
  visGroups(groupname = "Freunde",         color = "#868b91", shape = "ellipse") %>%
  visGroups(groupname = "Bekannte",        color = "#808080", shape = "ellipse") %>%
  visGroups(groupname = "Fremde",          color = "#b3bac2", shape = "ellipse") %>%
  visGroups(groupname = "Arbeitskollegen", color = "#e0e9f3", shape = "ellipse") %>%
  visGroups(groupname = "Ersttermin offen",  color = "#db3c30", shape = "ellipse") %>%
  visGroups(groupname = "Zweittermin offen", color = "#f6685e", shape = "ellipse") %>%
  visGroups(groupname = "Noch nicht kontaktiert", color = "#f1c232", shape = "ellipse") %>%

  visIgraphLayout(randomSeed = 123) %>%

  visEdges(smooth = list(enabled = TRUE, type = "diagonalCross")) %>%

  visInteraction(
    keyboard = TRUE,
    tooltipDelay = 0,
    hideEdgesOnDrag = TRUE,
    hoverConnectedEdges = TRUE
  ) %>%

  visOptions(
    highlightNearest = TRUE,
    selectedBy = "group",
    nodesIdSelection = TRUE,
  ) %>%

  visLegend() %>%

  addFontAwesome()

Error Message: Warning: Error in knit_params_get: render params not declared in YAML: params