Use User object in UserGetLanguageObject hook only when safe to load

In case of error formatting the context language may set up before the
Setup.php is ended.

Bug: T267445
Change-Id: I4f07b30f75922884867bd14d654effc0e26a47f4

includes/UniversalLanguageSelectorHooks.php

@@ -339,8 +339,8 @@ class UniversalLanguageSelectorHooks implements
 		if (
 			// uselang can be used for temporary override of language preference
 			$request->getText( 'uselang' ) ||
-			// Registered user: use preferences
-			!$user->isAnon()
+			// Registered user: use preferences, only when safe to load - T267445
+			( $user->isSafeToLoad() && $user->isRegistered() )
 		) {
 			return;
 		}