Unexpected result with kysely-planetscale

.env.example

PLANETSCALE_URL='mysql://foo:pscale_pw_bar@aws.connect.psdb.cloud/baz?ssl={"rejectUnauthorized":true}'

.nvmrc

22

index.test.mts

import { Kysely, MysqlDialect } from "kysely";
import { PlanetScaleDialect } from "kysely-planetscale";
import { createPool } from "mysql2";
import { strict as assert } from "node:assert";
import { describe, test } from "node:test";
import { fetch } from "undici";

describe("mysql", function () {
  const db = new Kysely({
    dialect: new MysqlDialect({
      pool: createPool({
        database: "mysql",
        host: "localhost",
        user: "root",
        password: "",
      }),
    }),
  });

  test("one row", async function () {
    const q = await db
      .selectFrom([
        db.selectNoFrom((eb) => eb.val(0).as("num_column")).as("foo"),
      ])
      .selectAll()
      .execute();

    assert.deepStrictEqual(q, [{ num_column: 0 }]); // ✅
  });

  test("two rows", async function () {
    const q = await db
      .selectFrom([
        db
          .selectNoFrom((eb) => eb.val(0).as("num_column"))
          .unionAll(db.selectNoFrom((eb) => eb.val(0).as("num_column")))
          .as("foo"),
      ])
      .selectAll()
      .execute();

    assert.deepStrictEqual(q, [{ num_column: 0 }, { num_column: 0 }]); // ✅
  });
});

describe("planetscale", function () {
  const db = new Kysely({
    dialect: new PlanetScaleDialect({
      url: process.env.PLANETSCALE_URL,
      fetch,
    }),
  });

  test("one row", async function () {
    const q = await db
      .selectFrom([
        db.selectNoFrom((eb) => eb.val(0).as("num_column")).as("foo"),
      ])
      .selectAll()
      .execute();

    assert.deepStrictEqual(q, [{ num_column: 0 }]); // ✅
  });

  test("two rows", async function () {
    const q = await db
      .selectFrom([
        db
          .selectNoFrom((eb) => eb.val(0).as("num_column"))
          .unionAll(db.selectNoFrom((eb) => eb.val(0).as("num_column")))
          .as("foo"),
      ])
      .selectAll()
      .execute();

    assert.deepStrictEqual(q, [{ num_column: 0 }, { num_column: 0 }]); // ❌ actual: [ { num_column: '0' }, { num_column: '0' } ]
  });
});

package.json

{
  "private": true,
  "type": "module",
  "scripts": {
    "test": "tsx --env-file=.env --test \"./*.test.mts\""
  },
  "devDependencies": {
    "@types/node": "^20.12.7",
    "tsx": "^4.7.3",
    "typescript": "^5.4.5"
  },
  "dependencies": {
    "@planetscale/database": "^1.17.0",
    "kysely": "^0.27.3",
    "kysely-planetscale": "^1.4.0",
    "mysql2": "^3.9.7",
    "undici": "^6.14.1"
  }
}

tsconfig.json

{
  "$schema": "https://json.schemastore.org/tsconfig",
  "compilerOptions": {
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "strict": true
  }
}