With MediaWiki 1.43 and Extension Version 4.5, I have seen "Error 1050: Table 'user_watch_scores' already exists" as part of Function: PageWatchesQuery::createUserWatchScoresTempTable. While this might be a transient error, it would be better to ensure the php handles cases where this could occur.

If the intent is to create it only when it doesn't exist, then could change line 139 of PageWatchesQuery.php
from

CREATE TEMPORARY TABLE user_watch_scores

to

CREATE TEMPORARY TABLE IF NOT EXISTS user_watch_scores

Otherwise, if the intent is to always create it each time, then you could modify to drop table if it exists, then create it. Lines 135 to 139
from:

private function createUserWatchScoresTempTable() {
		$dbw = WatchAnalyticsUtils::getWriteDB();

		$sql = <<<END
			CREATE TEMPORARY TABLE user_watch_scores

to:

private function createUserWatchScoresTempTable() {
		$dbw = WatchAnalyticsUtils::getWriteDB();
		$dbw->query( 'DROP TEMPORARY TABLE IF EXISTS user_watch_scores;', __METHOD__ );
		$sql = <<<END
			CREATE TEMPORARY TABLE user_watch_scores