Getting Source Maps to Work

## Environment

```
npx react-native info
info Fetching system and libraries information...
System:
OS: macOS 10.15.4
CPU: (12) x64 Intel(R) Core(TM) i9-8950HK CPU @ 2.90GHz
Memory: 1.26 GB / 32.00 GB
Shell: 3.2.57 - /bin/bash
Binaries:
Node: 14.1.0 - /usr/local/bin/node
Yarn: 1.10.1 - /usr/local/bin/yarn
npm: 6.14.4 - /usr/local/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
Managers:
CocoaPods: 1.9.1 - /usr/local/bin/pod
SDKs:
iOS SDK:
Platforms: iOS 13.4, DriverKit 19.0, macOS 10.15, tvOS 13.4, watchOS 6.2
Android SDK:
API Levels: 26, 27, 28, 29
Build Tools: 26.0.2, 27.0.3, 28.0.3, 29.0.1, 29.0.2
System Images: android-23 | Google APIs Intel x86 Atom_64, android-28 | Google APIs Intel x86 Atom, android-28 | Google Play Intel x86 Atom, android-29 | Google Play Intel x86 Atom
Android NDK: Not Found
IDEs:
Android Studio: 3.6 AI-192.7142.36.36.6392135
Xcode: 11.4.1/11E503a - /usr/bin/xcodebuild
Languages:
Java: 1.8.0_211 - /usr/bin/javac
Python: 2.7.17 - /usr/local/bin/python
npmPackages:
@react-native-community/cli: Not Found
react: 16.11.0 => 16.11.0
react-native: 0.62.2 => 0.62.2
npmGlobalPackages:
*react-native*: Not Found
```

## Question
Hey! I have a few questions, and I was hoping someone could help me.

I created a branch of a small reproducer project here: https://github.com/ScottPierce/kotlin-react-native/tree/Haul2020

I'm checking source-map support with Haul, to consider moving over to it. I've got a simple Kotlin javascript module that just throws an exception, and I wanted to see if I can get a stack trace that references my Kotlin sources and line numbers. The compiled Kotlin JS files are located in the `./lib` folder.

**1. Why am I getting the same client exception for everything? `Expected a string but was BEGIN_OBJECT`**

I'm getting a fairly useless stack-trace in the android client. I've gotten the same crash in the client for everything. Haul couldn't resolve the `kotlin` module, I got this exception. And I'm also seeing this exception when the client is throwing an exception.

Here is what I see:

React-native gives me a more useful exception, albeit without applying source-maps for some reason:

**2. My stacktraces don't seem to take advantage of source-maps. How do I get them to?**

**3. How can I get webpack to see my local modules npm modules?**

I'm following the instructions here: https://webpack.js.org/configuration/resolve/#resolvemodules

For some reason I can't get webpack to see and use the modules I have in my `node_modules_local` file. I've tried configuring it in my `webpack.config.js` and nothing seems to work. I've copied the modules into my `node_modules` directory for the time being which has allowed me to at least try and get this to work.