Low visibility into EdgeDB JS query builder

I wrote this script:

import { createClient } from "edgedb";
import e from "./dbschema/edgeql-js/index";
 
(async function () {
  const client = createClient();
 
  const newCharacters = [
    {
      portrayed_by: "Robert Downey Jr.",
      name: "Iron Man",
      movies: ["Iron Man", "Iron Man 2", "Iron Man 3"],
    },
    {
      portrayed_by: "Chris Evans",
      name: "Captain America",
      movies: [
        "Captain America: The First Avenger",
        "The Avengers",
        "Captain America: The Winter Soldier",
      ],
    },
    {
      portrayed_by: "Mark Ruffalo",
      name: "The Hulk",
      movies: ["The Avengers", "Iron Man 3", "Avengers: Age of Ultron"],
    },
  ];
 
  const query = e.params({ characters: e.json }, (params) => {
    const movies = e.for(
      e.op("distinct", params.characters.movies),
      (movie) => {
        return e
          .insert(e.Movie, {
            title: e.cast(e.str, movie),
          })
          .unlessConflict((movie) => ({
            on: movie.title,
            else: movie,
          }));
      }
    );
    // Iterate characters
    return e.for(e.json_array_unpack(params.characters), (character) => {
      // inserting each one
      return e.insert(e.Character, {
        name: e.cast(e.str, character.name),
        portrayed_by: e.cast(e.str, character.portrayed_by),
        //Iterate movies
        movies: e.assert_distinct(
          e.for(e.json_array_unpack(character.movies), (movieTitle) => {
            // Inserting and linking any that are missing
            return e.select(movies, () => ({
              filter_single: { title: e.cast(e.str, movieTitle) },
            }));
          })
        ),
      });
    });
  });
 
  console.log("query:", query.toEdgeQL());
  const result = await query.run(client, {
    characters: newCharacters,
  });
  console.log(result);
})();

The intent was to add newCharacters to my database, but it doesn’t work. The console output when I run it:

InvalidValueError: cannot index JSON array by text
    at RawConnection._parseErrorMessage (/Users/raddevon/Documents/projects/edgedb/troubleshooting/ts-qb-for-test/node_modules/edgedb/dist/baseConn.js:310:21)
    at RawConnection._executeFlow (/Users/raddevon/Documents/projects/edgedb/troubleshooting/ts-qb-for-test/node_modules/edgedb/dist/baseConn.js:918:34)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at RawConnection.fetch (/Users/raddevon/Documents/projects/edgedb/troubleshooting/ts-qb-for-test/node_modules/edgedb/dist/baseConn.js:970:17)
    at ClientConnectionHolder.retryingFetch (/Users/raddevon/Documents/projects/edgedb/troubleshooting/ts-qb-for-test/node_modules/edgedb/dist/baseClient.js:178:26)
    at Client.query (/Users/raddevon/Documents/projects/edgedb/troubleshooting/ts-qb-for-test/node_modules/edgedb/dist/baseClient.js:487:20)
    at null.<anonymous> (/Users/raddevon/Documents/projects/edgedb/troubleshooting/ts-qb-for-test/linked-object-per-nested-array-item.ts:65:18) {
  source: undefined
}

This tells me there is a problem and points to the line where I run my query before going cold and tracing into the client binding itself. Unfortunately, this isn’t very helpful. My query is long, and I don’t know what part of the query is the problem which makes it much harder to solve.