title: Warning Message: Column 'labels' is of unsupported type function
body: <p>I have this list column called "labels" that i'm unlisting to get a readable data frame. Everything is working well locally but when i run this on AWS shiny server it's throwing me this error below. I can share additional code snippets but wanted to get pointers on this error first, what could this be? </p>
  
  <p>Warning: Error in mutate_impl: Column <code>labels</code> is of unsupported type function</p>
  
  <pre><code>Stack trace (innermost first):
      110: &lt;Anonymous&gt;
      109: stop
      108: filtered
      107: as.data.frame
      106: eval
      105: eval
      104: %&gt;%
      103: &lt;reactive:filtered_closed&gt; [/srv/shiny-server/support-dashboard/server.R#74]
       92: filtered_closed
       91: tagList
       90: tag
       89: tags$h3
       88: h3
       87: tag
       86: tags$div
       85: div
       84: tag
       83: tags$div
       82: div
       81: valueBox
       80: vbox_fun [/srv/shiny-server/support-dashboard/server.R#179]
       79: shiny::renderUI
       78: func
       77: origRenderFunc
       76: output$vb_ratio
        1: runApp
  </code></pre>
  
  <p>My Session info on server: </p>
  
  <pre><code>    R version 3.4.3 (2017-11-30)
  Platform: x86_64-pc-linux-gnu (64-bit)
  Running under: Ubuntu 16.04.3 LTS
  
  Matrix products: default
  BLAS: /usr/lib/libblas/libblas.so.3.6.0
  LAPACK: /usr/lib/lapack/liblapack.so.3.6.0
  
  locale:
   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
   [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
   [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
   [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
   [9] LC_ADDRESS=C               LC_TELEPHONE=C            
  [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  loaded via a namespace (and not attached):
  [1] compiler_3.4.3
  </code></pre>
  
  <p>Update: Additional Information: 
  Loading the dataset from a global.R </p>
  
  <pre><code>issues &lt;- readRDS("/srv/shiny-server/support-dashboard/issues.rds")
  </code></pre>
  
  <p>Server.R snippet below. Note: issues is the df. labels is the list. </p>
  
  <pre><code>shinyServer(function(input, output) {
  
      filtered &lt;- reactive({
          unnest(issues, labels) %&gt;% # remove lists from labels. 
              rename(pr_key = pull_request.url, 
                     reported_by = user.login, 
                     associate = assignee.login, 
                     release = milestone.title) %&gt;%
              select(-ends_with("url"), -starts_with("user"), 
                     -starts_with("assignee"), -starts_with("milestone"), 
                     -title) %&gt;%
              filter(str_detect(name, "help wanted")) %&gt;%
              mutate(created_at = ymd(as.Date(created_at)), 
                     closed_at = ymd(as.Date(closed_at))) 
      })
  
      filtered_by_date &lt;- reactive({
          filtered() %&gt;%
              group_by(created_at) %&gt;%
              filter(
                  # created_at in df replacement in reactive. 
                  created_at &gt;= input$dateRange[1],
                  created_at &lt;= input$dateRange[2]
              ) %&gt;%
              summarise(n = n()) %&gt;%
              rename(created_date = created_at) %&gt;%
              rename(issues_count = n)
      })
  </code></pre>
  
  <p>Additional Packages Info: </p>
  
  <pre><code>Attaching package: ‘shinydashboard’
  
  The following object is masked from ‘package:graphics’:
  
      box
  
  Loading required package: methods
  ── Attaching packages ─────────────────────────────────────── tidyverse 1.2.1 ──
  ✔ ggplot2 2.2.1     ✔ purrr   0.2.4
  ✔ tibble  1.4.2     ✔ dplyr   0.7.4
  ✔ tidyr   0.8.0     ✔ stringr 1.2.0
  ✔ readr   1.1.1     ✔ forcats 0.2.0
  ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
  ✖ dplyr::filter() masks stats::filter()
  ✖ dplyr::lag()    masks stats::lag()
  Highcharts (www.highcharts.com) is a Highsoft software product which is
  not free for commercial and Governmental use
  
  Attaching package: ‘lubridate’
  
  The following object is masked from ‘package:base’:
  
      date
  
  [1] "/srv/shiny-server/support-dashboard"
  # A tibble: 3,387 x 89
  </code></pre>