Chore: Inbox Members API improvements (#3008)

- New Inbox Member APIs
- Return JSON errors for Platform APIs

app/controllers/platform/api/v1/users_controller.rb

@@ -7,8 +7,8 @@ class Platform::Api::V1::UsersController < PlatformController
 
   def create
     @resource = (User.find_by(email: user_params[:email]) || User.new(user_params))
-    @resource.confirm
     @resource.save!
+    @resource.confirm
     @platform_app.platform_app_permissibles.find_or_create_by(permissible: @resource)
   end