refactor(migrator): simplify originalAlias extraction in migrateNodeVersionManagerFile

Author: naokihaba

packages/cli/src/migration/migrator.ts

@@ -2050,7 +2050,7 @@ export function migrateNodeVersionManagerFile(
   const sourcePath = path.join(projectPath, '.nvmrc');
   const nodeVersionPath = path.join(projectPath, '.node-version');
   const content = fs.readFileSync(sourcePath, 'utf8');
-  const originalAlias = content.split('\n')[0]?.trim() ?? '';
+  const originalAlias = content.split('\n')[0].trim();
   const version = parseNvmrcVersion(originalAlias);
 
   if (!version) {