title: Error in mutate_impl(.data, dots) : Evaluation error: Only year, quarter, month, week, and day periods are allowed for an index of class Date
body: <p>I am using <code>Anomalize</code> package to detect the Anomalies, but I am getting the mentioned error even though I have defined the <code>Date</code> as index :</p>
  
  <p>Sample Code : </p>
  
  <pre><code>x &lt;- as.data.frame(data %&gt;%
    group_by(date,acc_id) %&gt;%
    summarise(count = as.numeric(n_distinct(d_id))) %&gt;%
    ungroup())
  
  x$acc_id &lt;- as.character(x$acc_id)
  
  x &lt;- x %&gt;% 
    tibbletime::as_tbl_time(index = date)
  
  
  x %&gt;%
    time_decompose(count, method = "twitter", trend = "2 months") %&gt;%
    anomalize(remainder, method = "gesd") %&gt;%
    time_recompose() %&gt;%
    plot_anomalies(time_recomposed = TRUE)
  </code></pre>
  
  <p>Error :  </p>
  
  <blockquote>
    <p>Error in mutate_impl(.data, dots) :    Evaluation error: Only year,
    quarter, month, week, and day periods are allowed for an index of
    class Date.</p>
  </blockquote>
  
  <pre><code>dput(head(x))
  
  structure(list(date = structure(c(17532, 17532, 17532,  17532, 17532, 17532), class = "Date"), acc_id = c("a44444",  "gg555", "0195459b-5809-4b54-89b5-1a4376c9f126",  "ggg6546", "hhjh77",  "hhjh68777"), count = c(3, 1, 1, 1,  1, 1)), .Names = c("date", "acc_id", "count"), row.names = c(NA, 
  -6L), class = c("tbl_time", "tbl_df", "tbl", "data.frame"), index_quo = ~date, index_time_zone = "UTC")
  </code></pre>
  
  <p>I have the objective to group by date and some other factor not alone with the date.</p>