https://ru.wikipedia.org API behaves much differently from the others.
https://en.wikipedia.org/w/api.php?action=query&format=json&prop=pageprops&generator=mostviewed&ppprop=wikibase_item&gpvimlimit=50&gpvimoffset=950 : 50 items are not present here yet it does not throw a server error.
Output:
{"batchcomplete":"","query":{"pages":{"-1":{"ns":-1,"title":"Special:GlobalUsage","special":""},"48370461":{"pageid":48370461,"ns":0,"title":"Al Jazeera","pageprops":{"wikibase_item":"Q13477"}},"60455502":{"pageid":60455502,"ns":0,"title":"Angel's Last Mission: Love","pageprops":{"wikibase_item":"Q63067137"}},"595394":{"pageid":595394,"ns":0,"title":"Anthony Bourdain","pageprops":{"wikibase_item":"Q426582"}},"52139":{"pageid":52139,"ns":0,"title":"Audrey Hepburn","pageprops":{"wikibase_item":"Q42786"}}, ....... ,"255195":{"pageid":255195,"ns":0,"title":"Zodiac Killer","pageprops":{"wikibase_item":"Q218148"}}}}}
https://ru.wikipedia.org/w/api.php?action=query&format=json&prop=pageprops&generator=mostviewed&ppprop=wikibase_item&gpvimlimit=50&gpvimoffset=250 : Here also 50 items are not present but it throws a server error. (with gpvimlimit=11 it works fine.)
{"error":{"code":"internal_api_error_BadMethodCallException","info":"[XQRpmwpAEDUAAFnJ5qwAAAAV] Caught exception of type BadMethodCallException","errorclass":"BadMethodCallException"},"servedby":"mw1288"}
Also in other en and other API's no error is thrown even if the limit exceeds 500 (it just returns 500 items or the limit whatever is lower).
Background: T215222: Recommendation API translation endpoint stopped working
[XQRm9gpAEDcAAJMJPRoAAAAK] /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiPageSet.php:1186 exception.message Call to a member function getPrefixedText() on a non-object (null) exception.trace #0 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiPageSet.php(798): ApiPageSet->processTitlesArray(array) #1 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiPageSet.php(720): ApiPageSet->initFromTitles(array) #2 /srv/mediawiki/php-1.34.0-wmf.8/extensions/PageViewInfo/includes/ApiQueryMostViewed.php(52): ApiPageSet->populateFromTitles(array) #3 /srv/mediawiki/php-1.34.0-wmf.8/extensions/PageViewInfo/includes/ApiQueryMostViewed.php(24): MediaWiki\Extensions\PageViewInfo\ApiQueryMostViewed->run(ApiPageSet) #4 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiPageSet.php(176): MediaWiki\Extensions\PageViewInfo\ApiQueryMostViewed->executeGenerator(ApiPageSet) #5 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiPageSet.php(140): ApiPageSet->executeInternal(boolean) #6 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiQuery.php(234): ApiPageSet->execute() #7 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiMain.php(1595): ApiQuery->execute() #8 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiMain.php(531): ApiMain->executeAction() #9 /srv/mediawiki/php-1.34.0-wmf.8/includes/api/ApiMain.php(502): ApiMain->executeActionWithErrorHandling() #10 /srv/mediawiki/php-1.34.0-wmf.8/api.php(87): ApiMain->execute() #11 /srv/mediawiki/w/api.php(3): include(string) #12 {main}