react-native: Deeplinking is being interrupted by "Cannot read property 'apply' of undefined".

Hi! I encountered the same problem and made a slight adjustment to this line, which seemed a bit off. The spread operation appeared unnecessary:

-      for (const registration of [...registrations]) {
+      for (const registration of registrations) {

To my surprise, this change fixed the issue cc @yungsters . The problem arose after upgrading from version 0.69 to 0.72. I have Hermes enabled.

The spread is required to allow listeners to be added and removed during the execution of the event callback.

So the idea is to make a copy of registrations? @javache But, since it is a Set, it should’ve been done without the conversion to an array, which is unnecessary, like this:

      for (const registration of new Set(registrations)) {

updated patch:

diff --git a/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js b/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js
index 6bd2025..ab63eff 100644
--- a/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js
+++ b/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js
@@ -109,7 +109,7 @@ export default class EventEmitter<TEventToArgsMap: {...}>
       Registration<$ElementType<TEventToArgsMap, TEvent>>,
     > = this._registry[eventType];
     if (registrations != null) {
-      for (const registration of [...registrations]) {
+      for (const registration of new Set(registrations)) {
         registration.listener.apply(registration.context, args);
       }
     }

It solves the issue, which seems to be caused by a bug in the JS engine/compiler/transpiler (?).

Essentially, it incorrectly converts a Set to an Array when using the spread operator, which can be reproduced like this:

         const registrations = new Set();

          registrations.add(1);

          registrations.add(2);

          registrations.add(3);

          console.log([...registrations].join(" ")); // logs [object Set], while it should be 1 2 3

          console.log(Array.from(registrations).join(" ")); // 1 2 3

I cannot reproduce it on https://hermesengine.dev/playground/, so I presume it is caused by Babel.

React Native v0.72 will include https://github.com/facebook/react-native/commit/2780ba38ff23f4c5e717b8fd8a733b649701f00c, which changes EventEmitter to throw a TypeError when addListener is called with a second argument that is not a function.

This should help everyone here narrow down the originating source of this error in order to find out where the non-function is coming from (and where to fix the root cause).

Hi! I encountered the same problem and made a slight adjustment to this line, which seemed a bit off. The spread operation appeared unnecessary:

-      for (const registration of [...registrations]) {
+      for (const registration of registrations) {

To my surprise, this change fixed the issue cc @yungsters . The problem arose after upgrading from version 0.69 to 0.72. I have Hermes enabled.

Here’s a complete patch file for anyone else who might be grappling with this issue:

diff --git a/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js b/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js
index 6bd2025..6b64e0c 100644
--- a/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js
+++ b/node_modules/react-native/Libraries/vendor/emitter/EventEmitter.js
@@ -109,7 +109,7 @@ export default class EventEmitter<TEventToArgsMap: {...}>
       Registration<$ElementType<TEventToArgsMap, TEvent>>,
     > = this._registry[eventType];
     if (registrations != null) {
-      for (const registration of [...registrations]) {
+      for (const registration of registrations) {
         registration.listener.apply(registration.context, args);
       }
     }

@olosegres @s123121 @taoqf Have you tried the workaround (adding check for undefined)? Does it solve your issues too?

Hey, When is this correction expected to be published?

I am also facing the same issue after upgrading from 066.4 to 0.70.6 reactnative

Same problem after update to 0.70.6

Upgrading from 0.67 to 0.70.6 and meet exactly this problem