So we are looking to add more guidance on this soon, but the short answer is you should not use helperText/errorText on an input inside of ion-item. However, helperText/errorText can be used on inputs that are not used inside of list/item views.
We have not been very clear about best practices surrounding items/lists in the past, and it’s something we are looking to do better with.
Instead, I recommend using ion-note below the list to clarify the intent of the input. Here is an example:
Incorrect Usage:
This examples uses helperText on an input inside of an item. Note the double border as mentioned previously.
Correct Usage:
This is using an ion-note below each list to clarify the inputs.