hotfix(medusa): Save empty metadata on line-items (#126)

packages/medusa/src/models/schemas/line-item.js

@@ -3,7 +3,8 @@
  ******************************************************************************/
 import mongoose from "mongoose"
 
-export default new mongoose.Schema({
+export default new mongoose.Schema(
+  {
     title: { type: String, required: true },
     description: { type: String },
     thumbnail: { type: String },
@@ -41,4 +42,6 @@ export default new mongoose.Schema({
     fulfilled_quantity: { type: Number, default: 0 },
     returned_quantity: { type: Number, default: 0 },
     metadata: { type: mongoose.Schema.Types.Mixed, default: {} },
-})
+  },
+  { minimize: false }
+)