Added check if return value is an array (hestiacp#1494)

* Added check if return value is an array

    foreach ($dns_cluster as $key => $value) {
        $v_dns_cluster = 'yes';
    }

Returned NULL when cluster is disabled causing  error in error log

2020/12/22 21:48:25 [error] 29766#0: *63 FastCGI sent in stderr: "PHP message: PHP Warning:  Invalid argument supplied for foreach() in /usr/local/hestia/web/edit/server/index.php on line 113" while reading response header from upstream, client: xx.xx.xx.xx, server: _, request: "POST /edit/server/ HTTP/1.1", upstream: "fastcgi://unix:/var/run/hestia-php.sock:", host: "dev.eris.nu:8083", referrer: "https://dev.text.xx:8083/edit/server/"

* Add spaces

Co-authored-by: Raphael Schneeberger <rs@scit.ch>

Author: jaapmarcus

web/edit/server/index.php

@@ -110,8 +110,10 @@
 exec (HESTIA_CMD."v-list-remote-dns-hosts json", $output, $return_var);
 $dns_cluster = json_decode(implode('', $output), true);
 unset($output);
-foreach ($dns_cluster as $key => $value) {
-    $v_dns_cluster = 'yes';
+if (is_array($dns_cluster)) {
+    foreach ($dns_cluster as $key => $value) {
+        $v_dns_cluster = 'yes';
+    }
 }
 
 // List Database hosts