If I put " " in the badges field of Special:SetSiteLink, the input is not trimmed and is parsed as an entity id, which then causes uncaught exception.

Unexpected non-MediaWiki exception encountered, of type "Wikibase\DataModel\Entity\EntityIdParsingException"
[12b28529] /wiki/Special:SetSiteLink Exception from line 64 of /Library/WebServer/Documents/php-master/extensions/Wikibase/vendor/wikibase/data-model/src/Entity/DispatchingEntityIdParser.php: The provided id serialization " " is not valid

Backtrace:
#0 /Library/WebServer/Documents/php-master/extensions/Wikibase/vendor/wikibase/data-model/src/Entity/DispatchingEntityIdParser.php(45): Wikibase\DataModel\Entity\DispatchingEntityIdParser->throwInvalidId(string)
#1 /Library/WebServer/Documents/php-master/extensions/Wikibase/repo/includes/specials/SpecialSetSiteLink.php(378): Wikibase\DataModel\Entity\DispatchingEntityIdParser->parse(string)
#2 /Library/WebServer/Documents/php-master/extensions/Wikibase/repo/includes/specials/SpecialSetSiteLink.php(451): Wikibase\Repo\Specials\SpecialSetSiteLink->parseBadges(array, Status)
#3 /Library/WebServer/Documents/php-master/extensions/Wikibase/repo/includes/specials/SpecialSetSiteLink.php(159): Wikibase\Repo\Specials\SpecialSetSiteLink->setSiteLink(Wikibase\DataModel\Entity\Item, string, string, array, Wikibase\Summary)
#4 /Library/WebServer/Documents/php-master/extensions/Wikibase/repo/includes/specials/SpecialModifyEntity.php(96): Wikibase\Repo\Specials\SpecialSetSiteLink->modifyEntity(Wikibase\DataModel\Entity\Item)
#5 /Library/WebServer/Documents/php-master/includes/specialpage/SpecialPage.php(376): Wikibase\Repo\Specials\SpecialModifyEntity->execute(NULL)
#6 /Library/WebServer/Documents/php-master/includes/specialpage/SpecialPageFactory.php(490): SpecialPage->run(NULL)
#7 /Library/WebServer/Documents/php-master/includes/Wiki.php(285): SpecialPageFactory::executePath(Title, RequestContext)
#8 /Library/WebServer/Documents/php-master/includes/Wiki.php(588): MediaWiki->performRequest()
#9 /Library/WebServer/Documents/php-master/includes/Wiki.php(447): MediaWiki->main()
#10 /Library/WebServer/Documents/php-master/index.php(49): MediaWiki->run()
#11 {main}

Version: master
Severity: normal
Whiteboard: u=dev c=backend p=0