Custom error object appears as [Object object]

[mozeryansky]

What version of Next.js are you using?

12.0.4

What version of Node.js are you using?

14.18.1

What browser are you using?

Firefox

What operating system are you using?

macOS

How are you deploying your application?

next

Describe the Bug

I'm using supabase with nextjs, a postgres error thrown is reported as "[object Object]" instead of the contents.

The issue originates in next-server.js and next-dev-server.js from:
const err = (0, _isError).default(error) ? error : error ? new Error(error + '') : null;

> error
{hint: 'If a new foreign key between these entities wa…the database, try reloading the schema cache.', message: 'Could not find a relationship between products and prices in the schema cache'}

> error + ''
'[object Object]'

Expected Behavior

To treat print the object as is instead of converting to a string.

To Reproduce

1. From the example npx create-next-app -e https://github.com/vercel/nextjs-subscription-payments nextjs-subscription-payments
2. Set the NEXT_PUBLIC_SUPABASE_URL and NEXT_PUBLIC_SUPABASE_ANON_KEY in the .env.local
3. npm run dev

The error is reproduced assuming the database isn't setup and causes the postgres error.

[mozeryansky]

Changing the line to stringify object errors resolves the issue, but I'm not sure it's the best approach.

var err = undefined
if (typeof error === "object") {
    err = JSON.stringify(error)
} else {
    err = (0, _isError).default(error) ? error : error ? new Error(error + '') : null;
}

[awareness481]

I believe changing

next.js/packages/next/server/next-server.ts

Line 2298 in cf64e91

const err = isError(error) ? error : error ? new Error(error + '') : null

to const err = isError(error) ? error : error ? new Error(JSON.stringify(error)) : null should be enough. Since this code appears a lot in the codebase it would probably be better to replace all its instances I'd guess.

Do you need help opening a PR @mozeryansky ?

As a sidenote, perhaps isError could be changed to && ( 'name' in err || 'message' in err)? (although this would probably require additional refactoring)

[mozeryansky]

@awareness481 Great suggestion. I'll make a PR now.

[mozeryansky]

The fix was simple but I had trouble testing a local built version of next. I ended up making the changes to the nextjs package in the node_modules folder in order to verify the changes. When I used a fresh checkout of nextjs and used yarn build the sample project would show a hook error

:

[Manikanta-20]

Facing same issue on iOS browsers(Safari, chrome, firefox)
Any comparability issues?
using nextjs + custom server (express.js) nextjs v10.2.3, node v14

[Karan190]

hey how to run your application. I can solve your issue.

[mozeryansky]

hey how to run your application. I can solve your issue.

I already solved it in PR #31866

[mozeryansky]

Except I can't get any maintainer to respond. I tried commenting in the PR a few times, and I've messaged a couple of them in Twitter directly. No response.

[Karan190]

Ok man. No issues

…

On Tue, 11 Jan, 2022, 12:27 am Michael Ozeryansky, ***@***.***> wrote: Except I can't get any maintainer to respond. I tried commenting in the PR a few times, and I've messaged a couple of the in Twitter directly. No response. — Reply to this email directly, view it on GitHub <#31670 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AKGMGYUSUAYURGXJWT2MZY3UVMTYVANCNFSM5IQBKZQQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you commented.Message ID: <vercel/next. ***@***.***>

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.