[flutter_tools] handle invalid yaml in plugin dependency (#63526)

packages/flutter_tools/lib/src/plugins.dart

@@ -311,7 +311,14 @@ Plugin _pluginFromPackage(String name, Uri packageRoot) {
   if (!globals.fs.isFileSync(pubspecPath)) {
     return null;
   }
-  final dynamic pubspec = loadYaml(globals.fs.file(pubspecPath).readAsStringSync());
+  dynamic pubspec;
+
+  try {
+    pubspec = loadYaml(globals.fs.file(pubspecPath).readAsStringSync());
+  } on YamlException catch (err) {
+    globals.printTrace('Failed to parse plugin manifest for $name: $err');
+    // Do nothing, potentially not a plugin.
+  }
   if (pubspec == null) {
     return null;
   }

packages/flutter_tools/test/general.shard/plugins_test.dart

@@ -908,6 +908,28 @@ flutter:
         FeatureFlags: () => featureFlags,
       });
 
+      testUsingContext('Invalid yaml does not crash plugin lookup.', () async {
+        when(macosProject.existsSync()).thenReturn(true);
+        when(featureFlags.isMacOSEnabled).thenReturn(true);
+        when(flutterProject.isModule).thenReturn(true);
+        // Create a plugin without a pluginClass.
+        dummyPackageDirectory.parent.childFile('pubspec.yaml')
+          ..createSync(recursive: true)
+          ..writeAsStringSync(r'''
+"aws ... \"Branch\": $BITBUCKET_BRANCH, \"Date\": $(date +"%m-%d-%y"), \"Time\": $(date +"%T")}\"
+    ''');
+
+        await injectPlugins(flutterProject, checkProjects: true);
+
+        final File registrantFile = macosProject.managedDirectory.childFile('GeneratedPluginRegistrant.swift');
+
+        expect(registrantFile, exists);
+      }, overrides: <Type, Generator>{
+        FileSystem: () => fs,
+        ProcessManager: () => FakeProcessManager.any(),
+        FeatureFlags: () => featureFlags,
+      });
+
       testUsingContext('Injecting creates generated Linux registrant', () async {
         when(linuxProject.existsSync()).thenReturn(true);
         when(featureFlags.isLinuxEnabled).thenReturn(true);