 <code>tryCatch()</code> the error
in the main R process. Then the error message is printed, but the actual
error object is lost, and you need to re-run the code in a <code>tryCatch()</code>,
hoping that it would produce the same error.</p>
<p>For a better workflow, whenever a callr error is uncaught, callr
assigns it to the <code>.Last.error</code> variable, that can be inspected.
Of course, a subsequent callr error will overwrite <code>.Last.error</code>, it works very
much like <code>.Last.value</code>, 