[fix] await send() never resolves if file is not found

## Describe the bug
using this example code:
await send(ctx, ctx.path, { root: __dirname + '/public' });
If the file is not found, the promise never resolves. This is a memory leak.

**Node.js version:**

**OS version:**

**Description:**

## Actual behavior

## Expected behavior

## Code to reproduce

## Checklist

- [ ] I have searched through GitHub issues for similar issues.
- [ ] I have completely read through the README and documentation.
- [ ] I have tested my code with the latest version of Node.js and this package and confirmed it is still not working.

Start with the reported await send(ctx, ctx.path, { root: __dirname + '/public' }) call and inspect the send implementation for the missing-file path. Reproduce the case with a nonexistent file; done means the promise settles instead of remaining unresolved.

Written by the indexing model from the issue text.