Haul server crashes when navigating to root url

[michens]

Environment

I am on Windows and node v14.15.1, but it looks like this should apply everywhere

Description

When you run haul, you get the following message: done ▶︎ Packager server running on http://localhost:8081 You can click on the link from the console, which opens localhost at the root This causes haul to crash

I see three places to change that would each mitigate this

1. Lowest level

callback({
  errors: null,
  platform,
  file: fs.readFileSync(filePath),
  mimeType,
});

https://github.com/callstack/haul/blob/dc0b201a0355c0e1c0be897aa9e4586c7e9b2e89/packages/haul-core-legacy/src/compiler/Compiler.js#L149

There needs to be error handling when reading a file. A simple try/catch that invokes callback with any errors would suffice

2. Intermediate level

if (fs.existsSync(filePath)) {
  send(Events.FILE_RECEIVED, {
    taskId: payload.taskId,
    filePath,
    mimeType: mime.lookup(payload.filename) || 'text/javascript',
  });
} else {
  send(Events.FILE_NOT_FOUND, {
    taskId: payload.taskId,
  });
}

https://github.com/callstack/haul/blob/dc0b201a0355c0e1c0be897aa9e4586c7e9b2e89/packages/haul-core-legacy/src/compiler/worker/initWorker.js#L82

existsSync returns true for directories, but there is no reason to send a directory path to the compiler. A check to ensure that the path is a file (e.g. with a call to statSync) would prevent this issue

3. Highest level

server.route({
    method: 'GET',
    path: '/{any*}',
    ...
})

https://github.com/callstack/haul/blob/dc0b201a0355c0e1c0be897aa9e4586c7e9b2e89/packages/haul-core/src/server/setupCompilerRoutes.ts#L46

This sends every unknown path to the compiler, which is not desirable for the root

Adding a simple redirect like the following to setupDevtoolRoutes.ts would catch this and help developers get to their expected destination

server.route({
  method: 'GET',
  path: '/',
  handler: (_, h) => h.redirect('/debugger-ui')
});

Reproducible Demo

This applies to every haul project