Convert empty string to 0 for property length in node:list

Author: dantleech

src/PHPCR/Shell/Console/Command/Phpcr/NodeListCommand.php

@@ -231,7 +231,7 @@ private function renderProperties($currentNode, $table, $spacers, $filter = null
                 sprintf(
                     '<property-type>%s (%s)</property-type>',
                     $this->formatter->getPropertyTypeName($property->getType()),
-                    implode(',', (array) $property->getLength())
+                    implode(',', (array) $property->getLength()) ? : '0'
                 ),
                 $valueCell,
             ));