fix: babel config.

tools/babel-preset.js

@@ -6,7 +6,9 @@ const plugins = [
   '@babel/plugin-proposal-object-rest-spread',
   '@babel/plugin-proposal-optional-catch-binding',
   '@babel/plugin-proposal-async-generator-functions',
-  '@babel/plugin-proposal-decorators',
+  ['@babel/plugin-proposal-decorators', {
+    legacy: true,
+  }],
   ['@babel/proposal-class-properties', {
     loose: true,
   }],