TypeError Cannot read properties of null (reading 'getItem')

[m-nathani]

🐛 Bug Report

App is breaking because of this bug,., we got an Typeerror exception raised in our sentry logs as attached in the screenshot below

To Reproduce

Here is the public link with trace of this error :
https://umai.sentry.io/share/issue/ab6e3304bc0e4c42a4737828c7d35a41/

../node_modules/.pnpm/[email protected]/node_modules/i18next-browser-languagedetector/dist/esm/i18nextBrowserLanguageDetector.js in localStorage.lookup at line 174:34

    if (lookupLocalStorage && localStorageAvailable()) {
      return window.localStorage.getItem(lookupLocalStorage) || undefined; // Undefined ensures type consistency with the previous version o {snip}    <------------------------ this line.
    }

Expected behavior

Not to have this error and handle window location api with checks

Currently getting : TypeErrorCannot read properties of null (reading 'getItem')

Your Environment

• runtime version: node 22
• i18next version: "i18next": "^23.16.5", "i18next-browser-languagedetector": "^8.0.0", "react-i18next": "^15.1.1",
• os: Linux

[adrai]

How does your i18next config look like? Are you setting the lookupLocalStorage option to null?
Nevertheless, v8.0.3 should address this.

[danielrentz]

@adrai I checked the code again, and the only idea I came up with how this could happen is, that there may be different window objects in the same script environment, one with localStorage, and another without (private browser tab, maybe in some test environment?). That could indeed bypass checking the existence of "localStorage" if it has been checked once before with the complete window.

An idea to fix this would be to create a Map<Window, boolean> that stores the check results per window instance. If you like, I would prepare another PR for this.

[adrai]

Ii really would love to have a reproducible example first.