Next.js: Invalid Unicode escape sequence from _buildManifest.js

[flybayer]

Bug report

Describe the bug

Roughly 5-10% of the time when starting the Next.js dev server in Blitz.js results in the below error in the browser immediately after first page load. This error shows in the dev error overlay and in the browser console.

SyntaxError: Invalid Unicode escape sequence        _buildManifest.js:1

Before 9.5.3, it would show as something like s is undefined.

Note: we do have concurrent mode enabled, so possibly it could have something to do with that?

To Reproduce

I'm unable to reliably reproduce, but here's how it happens:

1. npx blitz new testapp
2. cd testapp
3. yarn blitz start
4. Immediately click the localhost:3000 link as soon as it appears from the Next.js dev server
5. Repeat steps 3 & 4 until you see the error

Expected behavior

Should not error

System information

System:
OS: macOS 10.15.6
CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
Memory: 614.28 MB / 64.00 GB
Shell: 3.1.2 - /usr/local/bin/fish
Next.js: 9.5.3

[ShikChen]

Just hit this today. The HTTP response looks truncated with unclosed JSON. Is there any update?

[flybayer]

@ShikChen did you encounter this in a blitz project or regular next.js?

[ShikChen]

It's a blitz project.