$page->getParserOutput() can apparently return false, so seems a reasonable starting point
Change-Id: I5ee1996f19405d4c854900376a3588fb1b7bbb66
// Try the parser cache first
// getParserOutput will save to Parser cache if able
$pout = $page->getParserOutput( $popts );
+ if ( !$pout ) {
+ $this->dieUsage( "There is no revision ID {$page->getLatest()}", 'missingrev' );
+ }
if ( $getWikitext ) {
$this->text = $page->getRawText();
}