Merge pull request #3578 from annando/probe-warning

Avoid "Invalid argument" warning in probing.

src/Network/Probe.php

@@ -827,11 +827,13 @@ class Probe {
 			}
 		}
 
+		if (is_array($webfinger["aliases"])) {
 			foreach ($webfinger["aliases"] as $alias) {
 				if (substr($alias, 0, 5) == 'acct:') {
 					$data["addr"] = substr($alias, 5);
 				}
 			}
+		}
 
 		if (!isset($data["network"]) || ($hcard_url == "")) {
 			return false;