Test: evcxr (rust in jupyter) assigning array slice to variable with confusing message

test.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "ename": "Error",
     "evalue": "failed to resolve: use of undeclared type `Index`",
     "output_type": "error",
     "traceback": [
      "failed to resolve: use of undeclared type `Index`"
     ]
    }
   ],
   "source": [
    "let an_array = [0, 1, 2, 3, 4];\n",
    "let mid = &an_array[1..4]; // A slice of a: just the elements 1, 2, and 3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[1, 2, 3]"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "let an_array = [0, 1, 2, 3, 4];\n",
    "&an_array[1..4]"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Rust",
   "language": "rust",
   "name": "rust"
  },
  "language_info": {
   "codemirror_mode": "rust",
   "file_extension": ".rs",
   "mimetype": "text/rust",
   "name": "Rust",
   "pygment_lexer": "rust",
   "version": ""
  },
  "orig_nbformat": 4
 },
 "nbformat": 4,
 "nbformat_minor": 2
}

The second cell is fine though