How to handle Uncaught (in promise) TypeError: e.map is not a function.

You might face this kind of error in your lighting web component from your JavaScript file . Here are some of the possibilities of getting this type of error .

Case 1 :

Passing Wrong data to given field | Incorrect input to field | Invalid Format of input.

In my case I got this error when I was trying to pass options to my Picklist type field . Format of my given options was –

[{"value":"One","label":"One"}]

Where expected format was

JSON.parse([{"value":"One","label":"One"}])

Passing data in this format solved my issue . In your case you should check for input type of given field .