This error is not self-explanatory. We spent several days figuring out what was wrong with our implementation and then realized that we needed to use webhooks.addHandlers once after creating the Shopify object.
So, updating the error message can save lots of time to find the issue.
https://github.com/Shopify/shopify-api-js/blob/8eab1c7fe80eca2aac68859599be7e443672f7f0/packages/shopify-api/lib/webhooks/registry.ts#L119
This error is not self-explanatory. We spent several days figuring out what was wrong with our implementation and then realized that we needed to use webhooks.addHandlers once after creating the Shopify object.
So, updating the error message can save lots of time to find the issue.