VSCode extension editor's "Test Flow" conflicted with existing tsconfig

# Problem
When I click the "Test Flow" button, an error will appear

```
Unexpected error while handling message from webview:
Could not find Custom Add in {absolute path to project}/add.flyde.ts.
The following errors were thrown, and might be the reason the node is not properly resolved.
Errors: Error loading module "{absolute path to project}/add.flyde.ts": Unexpected token 'export'
```

# Possible Cause
After some fiddling around, I found out that changing the `module` to `NodeNext` and `moduleResolution` to `NodeNext` seems to make it work

# Steps to Reproduce
1. Init a regular npm project
2. Install `@flyde/core` using package manager
3. Create a Flyde flow
4. Add a custom code node (the add in the tutorial will do)
5. Import the custom code node
6. Click "Test Flow" (it should work)
7. Create a `tsconfig.json`
8. Change `module` to `ESNext` and `moduleResolution` to `ESNext`
9. Click "Test Flow" (expected to fail)

# Request
monorepo doesn't work either