v1.2.3: Fix error of not displaying the button Notify Me when product has one attribute?

QUESTION:

I user Magento 2.3.4 Enterprise Edition and module v1.2.3.

It works fine with the product has multiples option (size, colour, ..., etc) but if I create a product with one option (for example, size) only. It doesn't show the button Notify Me button for child product out of stock as below:

Please tell me how to fix this?

ANSWER:

To fix this error, please edit file app/code/Bss/ProductStockAlert/Plugin/Helper/ConfigurableHelper.php as below: 

Or download the attached file below and overwrite the current file on your site. 

If you have any other question or concern, please feel free to contact us. We'd be happy to support!