I have two files: index.ts and pixel.ts

Index has a bunch of functions and two classes

Pixel imports one of the classes and a function from index and instantiates the class, then passes it to the function.

I have this tsup config

/* eslint-disable no-var */
import { defineConfig, Options } from "tsup"
import pkg from './package.json'

var commonConfig: Options = {
  clean: true,
  splitting: false,
  sourcemap: true,
  env: {
    __VERSION__: JSON.stringify(`${pkg.version}.${Date.now()}`),
    __TARGET__: JSON.stringify("node"),
  },
  target: "node14",
  outDir: "dist",
}

export default defineConfig([
  {
    entry: [
      "src/pixel.ts"
    ],
    ...commonConfig,
    format: ["iife"],
    target: "es5",
    env: {
      ...commonConfig.env,
      __TARGET__: JSON.stringify("web"),
    }
  },
  // {
  //   entry: [
  //     "src/index.ts",
  //     "src/types.ts",
  //     "src/examples.ts",
  //   ],
  //   ...commonConfig,
  //   format: ["esm", "cjs"],
  //   dts: true,
  // },
])

...trying to cross compile esm modules, cjs modules for node14 and es5 for the web.

However, the output looks like this for the es5 build:

CLI Building entry: src/pixel.ts
CLI Using tsconfig: tsconfig.json
CLI tsup v6.2.2
CLI Using tsup config: /sdk/tsup.config.ts
CLI Target: es5
CLI Cleaning output folder
IIFE Build start
IIFE dist/pixel.global.js     47.72 KB
IIFE dist/pixel.global.js.map 40.93 KB
IIFE ⚡️ Build success in 62ms

Which then crashes with import declarations may only appear at top level of a module but obviously I want this pixel to work in very old browsers.

I call tsup like this:

tsup

and it reads the config file above in full.

Latest versions.