I've just submitted v5.1.4 of IH-5 for review by the plugin moderators and will post back here once it's available for download.

This release contains changes associated with the following GitHub issues:

#133: Correcting various PHP Notices.
#161: Correct undefined-constant warning on initial install.
#163: Admin edit-product link broken on zc156.
#168: Correct "Unable to determine the page link" after adding an image.
#169: Correct handling of the "Force canvas" setting.
#170: Correct admin image-generation for products that can't be placed into the cart.