Be more careful when setting metadata values FS#2514

This fixes a warning when setting $meta['relation']['firstimage']
using p_set_metadata.

inc/parserutils.php

@@ -386,9 +386,18 @@ function p_set_metadata($id, $data, $render=false, $persistent=true){
         if ($key == 'relation'){
 
             foreach ($value as $subkey => $subvalue){
-                $meta['current'][$key][$subkey] = !empty($meta['current'][$key][$subkey]) ? array_merge($meta['current'][$key][$subkey], $subvalue) : $subvalue;
-                if ($persistent)
-                    $meta['persistent'][$key][$subkey] = !empty($meta['persistent'][$key][$subkey]) ? array_merge($meta['persistent'][$key][$subkey], $subvalue) : $subvalue;
+                if(isset($meta['current'][$key][$subkey]) && is_array($meta['current'][$key][$subkey])) {
+                    $meta['current'][$key][$subkey] = array_merge($meta['current'][$key][$subkey], (array)$subvalue);
+                } else {
+                    $meta['current'][$key][$subkey] = $subvalue;
+                }
+                if($persistent) {
+                    if(isset($meta['persistent'][$key][$subkey]) && is_array($meta['persistent'][$key][$subkey])) {
+                        $meta['persistent'][$key][$subkey] = array_merge($meta['persistent'][$key][$subkey], (array)$subvalue);
+                    } else {
+                        $meta['persistent'][$key][$subkey] = $subvalue;
+                    }
+                }
             }
 
             // be careful with some senisitive arrays of $meta
@@ -396,10 +405,10 @@ function p_set_metadata($id, $data, $render=false, $persistent=true){
 
             // these keys, must have subkeys - a legitimate value must be an array
             if (is_array($value)) {
-                $meta['current'][$key] = !empty($meta['current'][$key]) ? array_merge($meta['current'][$key],$value) : $value;
+                $meta['current'][$key] = !empty($meta['current'][$key]) ? array_merge((array)$meta['current'][$key],$value) : $value;
 
                 if ($persistent) {
-                    $meta['persistent'][$key] = !empty($meta['persistent'][$key]) ? array_merge($meta['persistent'][$key],$value) : $value;
+                    $meta['persistent'][$key] = !empty($meta['persistent'][$key]) ? array_merge((array)$meta['persistent'][$key],$value) : $value;
                 }
             }