[BUG] [Immer 5.0.x] Uncaught TypeError: undefined is not a function (Object.assign)

[FKobus]

🐛 Bug Report

On older browsers (mobile) the immer polyfill for Object.assign doesn't get polyfilled correctly.
The error thrown is super generic. But with debugging boils down to this code:

function makeTrapsForGetters(getters) {
  return Object.assign({}, reflectTraps, {
    get: function get(state, prop, receiver) {
      return getters.hasOwnProperty(prop) ? getters[prop](state, prop, receiver) : Reflect.get(state, prop, receiver);
    },
    setPrototypeOf: function setPrototypeOf(state) {
      throw new Error("Object.setPrototypeOf() cannot be used on an Immer draft"); // prettier-ignore
    }
  });
}

Link to repro

Our repro is private.

To Reproduce

Just run immer on an old browser.

We used a HTC ONE M9
Chrome version: 40.0.2214.89

Observed behavior

Crashes completely the application

Expected behavior

Custom polyfill works.

Environment

• Immer version:
• Occurs with setUseProxies(true)
• Occurs with setUseProxies(false) (ES5 only)

Workaround,

Use immer 4.0.2. There the polyfill functions as expected.

This issue is created because of this issue that was closed: #477 (comment)

[mweststrate]

This code isn't in the sources, so must relate to the transpiler setup :/

…

On Tue, Dec 17, 2019 at 5:18 PM Ferry Kobus ***@***.***> wrote: 🐛 Bug Report On older browsers (mobile) the immer polyfill for Object.assign doesn't get polyfilled correctly. The error thrown is super generic. But with debugging boils down to this code: function makeTrapsForGetters(getters) { return Object.assign({}, reflectTraps, { get: function get(state, prop, receiver) { return getters.hasOwnProperty(prop) ? getters[prop](state, prop, receiver) : Reflect.get(state, prop, receiver); }, setPrototypeOf: function setPrototypeOf(state) { throw new Error("Object.setPrototypeOf() cannot be used on an Immer draft"); // prettier-ignore } }); } Link to repro Our repro is private. To Reproduce Just run immer on an old browser. We used a HTC ONE M9 Chrome version: 40.0.2214.89 Observed behavior Crashes completely the application Expected behavior Custom polyfill works. Environment - *Immer version:* - Occurs with setUseProxies(true) - Occurs with setUseProxies(false) (ES5 only) Workaround, Use immer 4.0.2. There the polyfill functions as expected. This issue is created because of this issue that was closed: #477 (comment) <#477 (comment)> — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#482?email_source=notifications&email_token=AAN4NBA2HI7O2LCGI6SDF2DQZECWNA5CNFSM4J362WEKYY3PNVWWK3TUL52HS4DFUVEXG43VMWVGG33NNVSW45C7NFSM4IBDTHUQ>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAN4NBGO2ABYWNM62I26T2DQZECWNANCNFSM4J362WEA> .

[mweststrate]

@egoist ideas?

[egoist]

@mweststrate You're using object rest spreading here so it gets transpiled to Object.assign:

immer/src/proxy.js

Line 364 in 7a8e4e4

...reflectTraps,

I guess you should change this to use your assign utility:

immer/src/common.js

Line 64 in 7a8e4e4

export const assign =

[mweststrate]

@egoist yeah that is what I assumed, but I guess that means that the transpilation config is off, as that should prevent us against such mistakes? Probably the target ES version is too high? If transpilation doesn't guard us against this we will run into it every time a spread is introduced :) IIRC babel shout emit utility functions for this automatically?

[aleclarson]

🎉 This issue has been resolved in version 5.0.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[mweststrate]

Pushed a patch, will revisit when finalizing TS conversion. @FBKobus could you confirm version 5.0.02 fixes the issue?

[FKobus]

@mweststrate I will test tomorrow on several old devices and report here the outcome.
Looking at the MR it seems to resolve to your internal polyfill, so i'm suspecting green flags

[FKobus]

@mweststrate ; hereby I confirm that the bug has been resolved in version 5.0.2.

[mweststrate]

Thanks!