parcel [serve] --lazy fails to load an async bundle under certain conditions

[rayinaway]

🐛 bug report

parcel [serve] fails to load an async bundle under the following conditions:

• --lazy flag is set.
• Along with the async bundle, the parent module statically imports some other module.
• Parcel cache has not been created yet.

These conditions seem exhaustive, a minimal repro below reflects that. After the cache is created, the next HMR invocation resolves the issue.

🎛 Configuration

Apart from the --lazy flag, out-of-the-box Parcel.

🤔 Expected Behavior

When the async bundle is requested, Parcel's development server responds with it.

😯 Current Behavior

When the async bundle is requested, the server responds with index.html as a fallback instead, and a SyntaxError from failed parsing is thrown.

dynamic.51313f62.js:1 Uncaught SyntaxError: Unexpected token '<'
index.63aff760.js:61 Uncaught (in promise) Error: Cannot find module 'kmWTC'
    at newRequire (index.63aff760.js:61:19)
    at Function.newRequire (index.63aff760.js:45:18)
    at runtime-647fb96160fc59b6.js:1:248

💁 Possible Solution

Might be related to how Parcel initializes the cache.

🔦 Context

Faced the issue when tried to dynamically import app-specific devtools under certain conditions only.

💻 Code Sample

https://github.com/rayinaway/lazy-serve-parcel-bug-repro

🌍 Your Environment

Software	Version(s)
Parcel	2.8.3
Node	16.13.2
npm	8.1.2
Operating System	Windows 10

[marcins]

This should be fixed by #9093.