Prevent errors if limitVisits is <= 0. (matomo-org#15336)

If set to 0 or less than 0, all rows will be removed from result set, but the code assumes at least one row exists, which results in errors.

plugins/Live/API.php

@@ -211,7 +211,7 @@ public function getVisitorProfile($idSite, $visitorId = false, $segment = false,
     {
         Piwik::checkUserHasViewAccess($idSite);
 
-        if ($limitVisits === false) {
+        if ($limitVisits <= 0) {
             $limitVisits = VisitorProfile::VISITOR_PROFILE_MAX_VISITS_TO_SHOW;
         } else {
             $limitVisits = (int) $limitVisits;