[Bug]: Nextcloud Files crashes Firefox

⚠️ This issue respects the following points: ⚠️

• This is not a troubleshooting question, general support matter, or webserver/proxy problem, but likely a bug (if unsure, ask the Community Help Forum).
• This issue is not already reported on Github OR solved at the Community Help Forum (I've searched!).
• I'm using a maintained major version of Nextcloud Server and tested against the latest patch level. (Supported major versions and current patch levels).
• I agree to follow Nextcloud's Code of Conduct.
• I've tried my best to provide clear reproduction steps that someone unfamiliar with this bug could use to reproduce it.

Bug description

When I open Nextcloud Files Firefox crashes. This is the Firefox crash report:

Tested on c.nc.com (35.0.0.7 (C2))
Firefox: 154.0 (64-bit)
Operating System: Fedora

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Interventions","userDisabled":false,"appDisabled":false,"foreignInstall":false,"hasBinaryComponents":false,"installDay":0,"quarantineIgnoredByApp":true,"quarantineIgnoredByUser":false},"newtab@mozilla.org":{"version":"156.2.20260824.60102","scope":1,"type":"extension","updateDay":20697,"isSystem":false,"isWebExtension":true,"multiprocessCompatible":true,"blocklisted":false,"description":"","name":"New Tab","userDisabled":false,"appDisabled":false,"foreignInstall":false,"hasBinaryComponents":false,"installDay":20599,"signedState":3,"signedTypes":"[2,1]","quarantineIgnoredByApp":true,"quarantineIgnoredByUser":false},"langpack-de@firefox.mozilla.org":{"version":"154.0.20260824.154132","scope":1,"type":"locale","updateDay":20697,"isSystem":false,"isWebExtension":true,"multiprocessCompatible":true,"blocklisted":false,"description":"Firefox Language Pack for Deutsch (de) – German","name":"Language: Deutsch (German)","userDisabled":false,"appDisabled":false,"foreignInstall":false,"hasBinaryComponents":false,"installDay":19662,"signedState":2,"signedTypes":"[2,1]","quarantineIgnoredByApp":false,"quarantineIgnoredByUser":false}},"theme":{"id":"default-theme@mozilla.org","blocklisted":false,"description":"Follow the operating system setting for buttons, menus, and windows.","name":"System theme — 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Throttleable: 1
TotalPageFile: 40950566912
TotalPhysicalMemory: 32360636416
URL: https://cloud.nextcloud.com/apps/files/files
UptimeTS: 11405.759099561
UtilityProcessStatus: Running
Vendor: Mozilla
Version: 154.0
useragent_locale: en-US
This report also contains technical information about the state of the application when it crashed.

Steps to reproduce

1. Try to open Nextcloud Files with Firefox
2. Firefox crashes, see crash report above

Note: Opening any other app: calender, talk,... works fine without crashing firefox

Expected behavior

Firefox opens Nextcloud Files without crashing

Nextcloud Server version

35

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

No response

Start by reproducing the crash at https://cloud.nextcloud.com/apps/files/files in Firefox 154 on Fedora, then compare it with the other Nextcloud apps that reportedly work. Use the supplied Firefox crash report to narrow the failure to the Files frontend; done means Files opens without crashing and the reproduction steps no longer trigger a crash.