title: Unable to load ggplot2 package
body: <p>I was trying to install emmeans using install_github and it required that I install rtools and after attempting this I not only was unsuccessful in installing emmeans with the following code:</p>
  
  <pre><code>    devtools::install_github("rvlenth/emmeans", dependencies = TRUE, build_opts = "")
  </code></pre>
  
  <p>Received this:</p>
  
  <pre><code>Error: Failed to install 'emmeans' from GitHub: System command 'Rcmd.exe' failed, exit status: 1, stdout + stderr: 
  checking for file 'C:\Users\jmb827\AppData\Local\Temp\RtmpYrGInN\remotes387066d354e0\rvlenth-emmeans-32bf444/DESCRIPTION' ... OK 
  preparing 'emmeans': 
  checking DESCRIPTION meta-information ... OK 
  checking for LF line-endings in source and make files and shell scripts 
  checking for empty or unneeded directories 
  looking to see if a 'data/datalist' file should be added 
  * building 'emmeans_1.4.5.009003.tar.gz' 
  
  ERROR 
  cannot change to directory ''
  </code></pre>
  
  <p>but now can not load <code>ggplot2</code> among other packages with error: </p>
  
  <pre><code>package �ggplot2� was built under R version 3.6.3Error: package or namespace load failed for ‘ggplot2’:
   package ‘tibble’ does not have a namespace
  </code></pre>