Cannot read properties of undefined (reading 'then')

[flumms]

----- UNHANDLED ERROR (IN BC) -----
Message: Uncaught TypeError: Cannot read properties of undefined (reading 'then')
Source: <url>/Scripts/Dialog.js:804:6
TypeError: Cannot read properties of undefined (reading 'then')
    at DialogLeave (<url>/Scripts/Dialog.js:804:6)
    at i (eval at t.evalScript (ebc://render.js:1:121539), <anonymous>:216:1207)
    at eval (eval at t.evalScript (ebc://render.js:1:121539), <anonymous>:216:1590)
    at https://furryzoi.github.io/Devious-Obligate-Great-Stuff/bundle.js?v=1773842627062:37:16968
    at i (eval at t.evalScript (ebc://render.js:1:121539), <anonymous>:216:1419)
    at eval (eval at t.evalScript (ebc://render.js:1:121539), <anonymous>:216:1590)
    at https://littlesera.github.io/LSCG/dev/bundle.js?v=1773842627063:59:55609
    at i (eval at t.evalScript (ebc://render.js:1:121539), <anonymous>:216:1419)
    at eval (eval at t.evalScript (ebc://render.js:1:121539), <anonymous>:216:1590)
    at https://littlesera.github.io/LSCG/dev/bundle.js?v=1773842627063:39:71144

----- Current context (most recent first) -----
> Function DialogLeave hook chain exit
> Function DialogLeave hook from DOGS
> Function DialogLeave hook from LSCG
> Function DialogLeave hook from LSCG
[unknown origin]

----- Debug report -----
Location: https://www.bondageprojects.elementfx.com/R126/BondageClub/
UA: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) electron-bondage-club/2.19.6 Chrome/144.0.7559.220 Electron/40.6.1 Safari/537.36
BC Version: R126
ModSDK Version: 1.2.0
Mods:
  - Bondage Club Extended (BCX): 1.1.12-STRICT-DEV-20260207162333
    repository: https://github.com/Jomshir98/bondage-club-extended
  - Echo的动作拓展-beta (动作拓展): 0.35.0-beta
    repository: https://github.com/SugarChain-Studio/echo-activity-ext
  - Echo的服装拓展-beta (服装拓展): 1.124.3-beta.0
    repository: https://github.com/SugarChain-Studio/echo-clothing-ext
  - Liko - Plugin Collection Manager (Liko's PCM): 1.3.7
    repository: Liko的插件管理器 | Plugin collection manager
  - BC - Image Uploader (Liko's Image Uploader): 1.3.1
    repository: 圖片拖曳上傳並分享 | Image to litterbox/uguu/imgbb/tmpfiles and share
  - Chat History Export Enhanced v2.1 (Liko's CHE Enhanced): 2.1.4
    repository: Enhanced chat room history export with 7-day cache
  - Liko's Custom Dressing Background (Liko's CDB): 1.4.1
    repository: 自訂更衣室背景 | Custom Dressing Background
  - Fantastic Ultimate Solution to Addon Management (FUSAM): 624e9f46
    repository: https://gitlab.com/Sidiousious/bc-addon-loader
  - Chat Music Controller (CMC): 1.0.1
    repository: 聊天室音樂控制器 | Chat Music Controller
  - Liko's Automatically create video. (Liko's ACV): 1.2.2
    repository: 自動創建影片 | Automatically create video.
  - Liko's Notify on Invite (Optimized) (Liko's NOI): 1.1
    repository: Liko的邀請通知器 | Liko's notify on invite.
  - Region switch (liko's Region switch): 1.2
    repository: 快速切換混合&女性區 | Region switch
  - Liko's WCE Profile Share (Liko's WPS): 1.1.1
    repository: WCE個人資料分享 | WCE Profile Share
  - Chat Auto Translator Script (CATS): 1.1.1
    repository: https://github.com/ciberweaboo/cats
  - Crazy Roster Add-on By Sin (CRABS): 1.3.2.6 Beta
    repository: https://github.com/sin-1337/CRABS
  - Bondage Club Auto React + (BCAR+): 0.7.10
    repository: https://github.com/DrBranestawm/BCAR
  - Bondage Club Tweaks (BCTweaks): B.0.7.9
    repository: https://github.com/agicitag/BCTweaks
  - Wholesome Club Extensions (WCE): 6.3.17
    repository: https://github.com/KittenApps/WCE.git
  - BCX Reset Button Disabler (BRBD): 1.0.0
    repository: https://github.com/ciberweaboo/brbd
  - Maid's Bondage Scripts (MBS): 1.10.11
    repository: https://github.com/bananarama92/MBS
  - LianChat (LianChat): 0.1.1
  - Bondage Club Responsive (Responsive): 0.6.6
    repository: https://github.com/dDeepLb/BC-Responsive
  - Little Sera's Club Games (LSCG): 0.8.7
    repository: https://github.com/littlesera/LSCG
  - Maya's Petplay Additions (MPA): 0.6.0
    repository: https://github.com/MayaTheFoxy/MPA
  - Ultra Bondage Club (ULTRAbc): 5.8.3
    repository: https://github.com/tetris245/ULTRAbc
  - BondageClub Responsive (BondageClub Responsive): 1.2.5
    repository: https://github.com/dynilath/BCResponsive
  - Community Information Addon (CIA) (cia): 0.4.0
  - Moon Cards Editor (MoonCE): 1.2.21
    repository: https://github.com/LunarKitsunify/MoonCE
  - Devious Obligate Great Stuff (DOGS): 2.0.4
    repository: https://github.com/FurryZoi/Devious-Obligate-Great-Stuff.git
  - Bondage Club Chaos (BCC): 2.1.0
    repository: https://github.com/FurryZoi/Bondage-Club-Chaos
No known legacy mods detected.

----- BC state report -----
Mouse position: -1 -1
Connected to server: true
Local time: 1773842649638
Server time: 1773842647672.2979 (diff: -1965.70)
Screen: Online/ChatRoom
In chatroom: true
GLVersion: webgl2
Last received message: ChatRoomMessage (1773842648616)
Last sent message: ChatRoomCharacterArousalUpdate (1773842649249)

----- ModSDK report -----
Functions overwritten by non-ModSDK mods:
  - Player.GetDeafLevel: 5E80A3DC

This issue came when using Electron BC only, but normal at browser.

If you take a look at other people's profile or (sometimes) create a new room, this error came up with same messages

Message: Uncaught TypeError: Cannot read properties of undefined (reading 'then')

[dynilath]

I was unable to reproduce this error. I suggest you first try clicking "Tools" -> "Refresh Page" (the "Refresh Page" option within the EBC menu performs a no-cache refresh by default).
The root cause of this error appears to be a specific XXXLoad function did not correctly pass a Promise; given that the error manifests differently across various platforms, I suspect it may be related to cache refreshing.
(Note: EBC's resource cache does not cache HTML or JavaScript files; caching for these resources is controlled internally by the Chromium engine.)
The issue that XXXLoad did not returning a Promise stems from incorrect implementations in certain mods. EBC makes no modifications to these Load functions; therefore, I suspect you could also check the list of mods configured as "local"

[flumms]

Damn, I thought it was from Electron stuff. Thank you for the help and sorry to bother.