Unstub $wgLang before passing it to DiscussionParser::getTextSnippet()
Unstub $wgLang before passing it to DiscussionParser::getTextSnippet()

getTextSnippet() has a `Language` type hint that will fatal if $wgLang
is a StubUserLang object, so make sure we unstub it if nothing else
already has.

Bug: T118542
Change-Id: I847680074fbbf95bbe3b6002151d2a18c45ebe6e

wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo