When editing a recipe that produces a product, the "Produces product" field is always empty

[Hydration2705]

When you press edit on an existing recipe, the "Produces product" field is empty regardless of whether the recipe is set to produce a product or not. If you enter a product in the field and click the save button, it successfully shows the updated "Produced product" value in the Grocy webapp, so the field is working correctly otherwise.

This is pretty inconvenient since, from within the mobile app, there is no way to determine if a recipe produces a product or not. In addition, it is also not clear how to change a recipe so it no longer creates a product (or if it even worked).

To reproduce:

1. Edit or create a recipe so that it produces a product, then click save.
2. Edit the recipe from step 1.

Expected behaviour: The product saved in step 1 would be listed in the "Produces Product" field.
Actual behaviour: The "Produces product" field is empty as if the recipe does not produce a product.

I'm on v3.5.2, just FYI