title: R can not find fonts to be used in plotting
body: <p>I was using R 3.5.2. on Mac Mojave 10.14.4. Since a couple days have problems with text in my standard plots. Drawing plots with ggplot doesn't work either. I'm getting messages saying : </p>
  
  <p>For standard plots :</p>
  
  <blockquote>
    <p>Warning messages:
    1: In doTryCatch(return(expr), name, parentenv, handler) :
     no font could be found for family "Arial"</p>
  </blockquote>
  
  <p>For plots with ggplot2 :</p>
  
  <blockquote>
    <p>Error in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y,<br>
    : polygon edge not found</p>
  </blockquote>
  
  <p>Any suggestions how I can proceed to find the problem and solved are welcome?</p>
  
  <p>The following steps I already have tried :</p>
  
  <ol>
  <li>Go to the Font book and reactive disabled font. Restart computer</li>
  <li>Upgrading R to R 3.6.0.</li>
  <li>I can use <code>par(family = "Arial")</code> as a workaround each time for standard plots, but this won't work for ggplot2.</li>
  <li>Reinstalled standard fonts in font book.</li>
  <li>I installed the packages extrafont in R. When typing fonts() all fonts are shown to be installed.</li>
  </ol>
  
  <p>According MacOSX the fonts are alle installed, active and no duplicates present, but I still can't access them with R.</p>
  
  <p>This is the code I'm testing with :</p>
  
  <pre><code>x &lt;- seq(1, 10,1)
  y &lt;- rnorm(10, 4,1)
  plot(y~x)
  
  library(ggplot2)
  
  # Basic normal curve
  p  &lt;- ggplot(data.frame(x = c(-4, 4)), aes(x = x)) +
    stat_function(fun = dnorm, size=1.5)
  p
  </code></pre>