It calls resolveAlias, gets an array back, then calls getTitleFor with the result. getTitleFor expects a string, so always throws an exception.
We can either fix getTitleForAlias (just call getTitleFor) with the first element of the array returned by resolveAlias), or delete it and its sole usage in the deprecated function SpecialPage::getTitleForAlias
Version: 1.24rc
Severity: normal