Added specific error handler for java.lang.Throwable. The catch-all (defined with neither
error-code nor exception-type) seems to not get triggered when an exception
occurs within an exception handler. In at least Tomcat 10.1 (and likely many/all other versions), this
results in falling through to Tomcat's default error handler that shows a stack trace. Adding a specific
error handler for java.lang.Throwable appears to resolve this issue.