Issue #3167036 by gapple, anu.a_zyxware, thalles, larowlan: Empty...

Issue #3167036 by gapple, anu.a_zyxware, thalles, larowlan: Empty *.libraries.yml file can cause fatal error

core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php

@@ -341,7 +341,7 @@ protected function parseLibraryInfo($extension, $path) {
     $library_file = $path . '/' . $extension . '.libraries.yml';
     if (file_exists($this->root . '/' . $library_file)) {
       try {
-        $libraries = Yaml::decode(file_get_contents($this->root . '/' . $library_file));
+        $libraries = Yaml::decode(file_get_contents($this->root . '/' . $library_file)) ?? [];
       }
       catch (InvalidDataTypeException $e) {
         // Rethrow a more helpful exception to provide context.

core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryParserTest.php

@@ -644,6 +644,24 @@ public function testNonCoreLibrariesNotFound() {
     $this->assertEquals('libraries/third_party_library/css/example.css', $library['css'][0]['data']);
   }
 
+  /**
+   * @covers ::parseLibraryInfo
+   */
+  public function testEmptyLibraryFile() {
+    $this->moduleHandler->expects($this->atLeastOnce())
+      ->method('moduleExists')
+      ->with('empty')
+      ->will($this->returnValue(TRUE));
+
+    $path = __DIR__ . '/library_test_files';
+    $path = substr($path, strlen($this->root) + 1);
+    $this->libraryDiscoveryParser->setPaths('module', 'empty', $path);
+
+    $libraries = $this->libraryDiscoveryParser->buildByExtension('empty');
+
+    $this->assertEquals([], $libraries);
+  }
+
 }
 
 /**

core/tests/Drupal/Tests/Core/Asset/library_test_files/empty.libraries.yml

+# This file intentionally left empty