Merge branch '107_cache_system_node_provider' of https://github.com/MLoureiro/uuid into MLoureiro-107_cache_system_node_provider

src/Provider/Node/SystemNodeProvider.php

@@ -25,7 +25,7 @@ class SystemNodeProvider implements NodeProviderInterface
     /**
      * Returns the system node ID
      *
-     * @return string System node ID as a hexadecimal string
+     * @return string|false System node ID as a hexadecimal string, or false if it is not found
      */
     public function getNode()
     {
@@ -40,6 +40,7 @@ class SystemNodeProvider implements NodeProviderInterface
 
         // Search the ifconfig output for all MAC addresses and return
         // the first one found
+        $node = false;
         if (preg_match_all($pattern, $this->getIfconfig(), $matches, PREG_PATTERN_ORDER)) {
             $node = $matches[1][0];
             $node = str_replace([':', '-'], '', $node);