Cannot Build files on Windows with absolute, or relative paths

Our goal:

We are taking 2 .ts files and building them with tsup
We output the build in another directory for later use
This process is working flawlessly on Unix based OS (Mac, Linux, WSL)
We would like to expand our library to support users running Windows

Problem:

Once files are located via Glob, we verify their existence with fs.existsSync() which return true
We then pass an array of the file paths to build as seen below:

export async function compileWalletSetupFunctions(
  walletSetupDir: string,
  debug: boolean
) {
  const outDir = path.join(ensureCacheDirExists(), OUT_DIR_NAME);

  // Use a normalized glob pattern
  const globPattern = path.join(walletSetupDir, '**', '*.setup.{ts,js,mjs}');

  // Use glob to find files, ensuring proper path handling
  const fileList = await glob(globPattern, { absolute: true, windowsPathsNoEscape: true });

  if (debug) {
    console.log('[DEBUG] Found the following wallet setup files:');
    console.log(fileList, '\n');
  }

  // TODO: This error message is copied over from another function. Refactor this.
  if (!fileList.length) {
    throw new Error(
      [
        `No wallet setup files found at ${walletSetupDir}`,
        'Remember that all wallet setup files must end with `.setup.{ts,js,mjs}` extension!'
      ].join('\n')
    );
  }

  try {
    await build({
      name: 'cli-build',
      silent: true,
      entry: fileList,
      clean: true,
      outDir,
      format: 'esm',
      splitting: true,
      sourcemap: false,
      config: false,
      // TODO: Make this list configurable.
      external: ['@synthetixio/synpress', '@playwright/test', 'playwright-core', 'esbuild', 'tsup'],
      banner: {
        js: FIXES_BANNER
      },
      esbuildOptions(options) {
        // TODO: In this step, if the debug file is present, we should modify `console.log` so it prints from which file the log is coming from.
        // We're dropping `console.log` and `debugger` statements because they do not play nicely with the Playwright Test Runner.
        options.drop = debug ? [] : ['console', 'debugger']
      }
    })
  } catch (e) {
    console.log(e)
  }
  return outDir
}

An error occurs at ts normalizeOptions(): error Error within compile PrettyError file: Cannot find C:\Users\**\**\**\reponame\filepath\filename.ts
I've tried to convert to url and passed file:\\C:\Users\**\**\**\reponame\filepath\filename.ts and there I'd get another issue: ERR_UNSUPPORTED_ESM_URL_SCHEME
I've also tried non absolute paths, with no luck.

At my whits end as I've read most of the issues in the repo, maybe I'm missing something super obvious but any help would be appreciated.

egoist / tsup

Cannot Build files on Windows with absolute, or relative paths #1150

Our goal:

Problem:

Resources: