toolexit on malformed yaml (#123167)

[flutter_tools] toolexit on malformed yaml during gen-l10n

packages/flutter_tools/lib/src/localizations/localizations_utils.dart

@@ -5,6 +5,7 @@
 import 'package:meta/meta.dart';
 import 'package:yaml/yaml.dart';
 
+import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/logger.dart';
 import 'gen_l10n_types.dart';
@@ -436,7 +437,12 @@ LocalizationOptions parseLocalizationsOptions({
   if (contents.trim().isEmpty) {
     return const LocalizationOptions();
   }
-  final YamlNode yamlNode = loadYamlNode(file.readAsStringSync());
+  final YamlNode yamlNode;
+  try {
+    yamlNode = loadYamlNode(file.readAsStringSync());
+  } on YamlException catch (err) {
+    throwToolExit(err.message);
+  }
   if (yamlNode is! YamlMap) {
     logger.printError('Expected ${file.path} to contain a map, instead was $yamlNode');
     throw Exception();

packages/flutter_tools/test/general.shard/build_system/targets/localizations_test.dart

@@ -98,4 +98,19 @@ use-deferred-loading: string
       throwsException,
     );
   });
+
+  testWithoutContext('parseLocalizationsOptions tool exits on malformed Yaml', () async {
+    final FileSystem fileSystem = MemoryFileSystem.test();
+    final File configFile = fileSystem.file('l10n.yaml')..writeAsStringSync('''
+template-arb-file: {name}_en.arb
+''');
+
+    expect(
+      () => parseLocalizationsOptions(
+        file: configFile,
+        logger: BufferLogger.test(),
+      ),
+      throwsToolExit(),
+    );
+  });
 }