title: ggmosaic error message: default method not implemented for type 'list'
body: <p>Trying to create a heatmap using <code>ggmosaic</code>, I keep getting the error <code>Error in is.finite(x) : default method not implemented for type 'list'</code></p>
  <p>Searching for that error message, one answer was that &quot;This error is because the is.infinite() and the is.finite() functions are not implemented with a method for data.frames.&quot; <a href="https://stackoverflow.com/questions/8173094/how-to-check-a-data-frame-for-any-non-finite">But not a useful solution in the question nor about ggmosaic</a></p>
  <h1></h1>
  <p>Even the example from the vignette fails for me.</p>
  <pre><code>ggplot(data = NHANES) +
     geom_mosaic(aes(weight = Weight, x = product(SleepHrsNight), fill=factor(SleepHrsNight)), na.rm=TRUE) +
     labs(x=&quot;Hours of sleep a night &quot;, title='f(SleepHrsNight)') + guides(fill=guide_legend(title = &quot;SleepHrsNight&quot;, reverse = TRUE))
  </code></pre>
  <p>My system is Windows, RStudio, R version one before the most current, and <code>ggmosaic</code> Ver 0.1.2</p>
  <p>The made-up data frame I want to use is</p>
  <pre><code>structure(list(Diversity = structure(c(1L, 5L, 4L, 5L, 1L, 2L, 
  2L, 2L, 4L, 1L, 5L, 4L, 5L, 4L, 2L, 3L, 3L, 1L, 5L, 2L, 1L, 4L, 
  3L, 3L, 3L), .Label = c(&quot;AfricanAm&quot;, &quot;Asian&quot;, &quot;Cauc.&quot;, &quot;Latino&quot;, 
  &quot;Other&quot;), class = &quot;factor&quot;), Office = structure(c(1L, 2L, 1L, 
  3L, 4L, 5L, 2L, 4L, 5L, 3L, 4L, 4L, 1L, 2L, 3L, 4L, 1L, 5L, 5L, 
  1L, 2L, 3L, 2L, 3L, 5L), .Label = c(&quot;Hamlet&quot;, &quot;MainTown&quot;, &quot;Metroprole&quot;, 
  &quot;Smithville&quot;, &quot;Urbanburg&quot;), class = &quot;factor&quot;), JrAssoc = c(1, 
  1, 1, 1, 1, 1, 2, 2, 2, 4, 4, 1, 1, 1, 2, 2, 3, 3, 3, 5, 5, 2, 
  5, 9, 10), SrAssPtr = c(2, 2, 1, 1, 3, 2, 1, 4, 4, 5, 1, 1, 3, 
  5, 7, 3, 2, 1, 1, 1, 1, 2, 3, 4, 4)), row.names = c(NA, -25L), .Names = c(&quot;Diversity&quot;, 
  &quot;Office&quot;, &quot;JrAssoc&quot;, &quot;SrAssPtr&quot;), class = c(&quot;tbl_df&quot;, &quot;tbl&quot;, 
  &quot;data.frame&quot;))
  </code></pre>
  <p>This code has not succeeded:</p>
  <pre><code>ggplot(diverse) +
    geom_mosaic(aes(weight = 1, x = product(JrAssoc, SrAssPtr), fill = Diversity))
  </code></pre>
  <p>Thank you for any guidance.</p>