Fix places where potential null handling was missing

New versions of Psalm will start detecting them soon, so
better we fix the in advance. Note that it's rare to get
those 2 cases reproduced in real life, because other
validations will fail earlier if those XML are corrupt,
but better have the case covered there.

Author: stronk7

src/Bridge/Vendors.php

@@ -50,9 +50,10 @@ public function __construct($path)
      */
     public function getVendorPaths()
     {
-        $base  = dirname($this->path);
-        $paths = [];
-        foreach ($this->xml->xpath('/libraries/library/location') as $location) {
+        $base      = dirname($this->path);
+        $paths     = [];
+        $locations = $this->xml->xpath('/libraries/library/location') ?? false ?: [];
+        foreach ($locations as $location) {
             $location = trim((string) $location, '/');
             $location = $base . '/' . $location;
 

src/PluginValidate/Finder/TableFinder.php

@@ -36,9 +36,10 @@ public function findTokens($file, FileTokens $fileTokens): void
      */
     protected function findTables(string $file): array
     {
-        $tables = [];
-        $xml    = simplexml_load_file($file);
-        foreach ($xml->xpath('TABLES/TABLE') as $element) {
+        $tables   = [];
+        $xml      = simplexml_load_file($file);
+        $elements = $xml->xpath('TABLES/TABLE') ?? false ?: [];
+        foreach ($elements as $element) {
             if (isset($element['NAME'])) {
                 $tables[] = (string) $element['NAME'];
             }