fix: update MyInfo field count correctly, show correct error

[mantariksh]

Problem

1. When user attempts to save more MyInfo fields than is allowed, a generic error message shows in the Toastr, rather than the specific one returned by the backend.
2. On the build tab, MyInfo field count does not update upon creation of MyInfo field.

Solution

Fixing error message

The initial error message was:

This was fixed by accessing error.response.status rather than error.status, since error is now an AxiosError.

The error message then changed to this:

This was because we return a 422 when an error occurs while editing fields, and the switch case handles 422s by attempting to access error.data.message. This was fixed by accessing error.response.data.message instead.

This finally fixed the error message:

Updating MyInfo field count

This was fixed by assigning to $scope.myform.form_fields instead of pushing to the array, which triggers the AngularJS digest cycle correctly.

[karrui]

lgtm