title: File not found issue in "rdrop2" (shiny)
body: <p>I want to delete a file from my Dropbox folder in a Shiny app using "rdrop2". But unfortunately I get an error, which I don't see why. </p>
  
  <p>My code is:</p>
  
  <pre><code>library(rdrop2)
  print(drop_exists("Edata"))
  x &lt;- drop_dir("Edata")
  print(x)
  drop_delete("Edata/sil.txt")
  </code></pre>
  
  <p>The output I observe is given below</p>
  
  <p>[1] FALSE</p>
  
  <p>**# A tibble: 6 x 11
    .tag   name  path_lower path_display id    client_modified server_modified rev    size is_downloadable content_hash
                                                         <br>
  1 folder dene~ /edata/de~ /edata/dene~ id:Y~ NA              NA              NA       NA NA              NA<br>
  2 file   DB1.~ /edata/db~ /edata/DB1.~ id:Y~ 2019-06-15T21:~ 2019-06-15T21:~ 11b6~   314 TRUE            16fbbd0ba84~
  3 file   DB 2~ /edata/db~ /edata/DB 2~ id:Y~ 2019-06-15T21:~ 2019-06-15T21:~ 11b6~   202 TRUE            3f6029c71b8~
  4 file   DB 0~ /edata/db~ /edata/DB 0~ id:Y~ 2019-06-15T21:~ 2019-06-15T21:~ 11b6~   337 TRUE            56bd60dc921~
  5 file   DB_0~ /edata/db~ /edata/DB_0~ id:Y~ 2019-06-15T21:~ 2019-06-15T21:~ 11b6~   380 TRUE            036b125a739~
  6 file   sil.~ /edata/si~ /edata/sil.~ id:Y~ 2019-06-20T22:~ 2019-06-20T22:~ 11b8~    11 TRUE            a0848be3e4f~*</p>
  
  <p><strong>Warning: Error in drop_delete: File not found on current path</strong></p>
  
  <p>I am puzzled because</p>
  
  <ul>
  <li>drop_exists("Edata") returns FALSE, which means that the folder
  "Edata" does not exist at the root of the Dropbox account,</li>
  <li>however, drop_dir("Edata") lists the folder and its content correctly,</li>
  <li>and when I try to delete an existing file ("sil.txt") using drop_delete("Edata/sil.txt") an error is thrown.</li>
  </ul>
  
  <p>What am I missing here?</p>