Expected a valid shop query parameter

This issue should no longer occur. However, if you know how to recreate it, I'd appreciate it if you could share your insights.

Sometimes, you may notice a black screen with the "Expected a valid shop query parameter" error. Generally, this occurs when the app authenticates the user.

To work around it, please open the app with the shop parameter populated in the address bar, i.e. add ?shop=mystorename.myshopify.com. For example, if your store's myshopify domain was galmis-test.myshopify.com, please open https://galmis-test.myshopify.com/admin/apps/select-customer-with-barcode-1/auth?shop=galmis-test.myshopify.com.

After successfully loading the app, the error should no longer occur.