Access your console to see the messages, warnings and errors posted by Discount Ninja. Here's how to do that on Firefox and Google Chrome.

The app adds a "welcome message" to the console.
This lets you know the app is properly installed and working on your shop:

Error messages posted by the app to the console help our engineers to understand problems with the app on your shop. They always start with the words Discount Ninja.
Example:

If an error occurs on your store, please contact support.

You may find messages in the console that appear to come from Discount Ninja, but that do not start with the words Discount Ninja, but do not originate in the app and do not indicate problems with the app.

Discount Ninja is only reporting these errors, they are not related to the app. They do not indicate an error with the Discount Ninja app, but they can be indicative of problems with other scripts or apps on your store.

The easiest way to check that is to temporarily disable Discount Ninja and then check your console again (open a new tab). This article explains how to disable the app.

That happens because Discount Ninja's script "listens" to a number of HTTP requests that your shop makes to detect, among other things, "add to cart" events that the app may need to react to. When errors happen in HTTP requests that the app listens to, Discount Ninja will add those error messages to the console. While those messages show that Discount Ninja added them to the console, they really indicate a problem with the HTTP request made and the system that relies on those requests may be impacted.