Setting key as expand trigger overrides previous mapping of that key

[SimonKvantdator]

I use <c-j> as my expand trigger. But if there is no snippet to expand, I want <c-j> to do nothing, so I have added a line, imap <c-j> <nop> to my init.vim. But once I set <c-j> as my expand trigger, this mapping gets overwritten.

Expected behavior: <c-j> does nothing if there is no snippet to expand

Actual behavior: <c-j> does what it does by default, inserts a newline I think.

Steps to reproduce I have this in my init.vim:

let g:plugged_home = '~/.vim/plugged'
imap <c-j> <nop>
et g:UltiSnipsExpandTrigger = '<c-j>'
let g:UltiSnipsJumpForwardTrigger = '<c-j>'
call plug#begin(g:plugged_home)
    Plug 'sirver/ultisnips'
call plug#end()

---

• Operating System: Ubuntu 20.04.4
• Vim Version: NVIM v0.4.3 Build type: Release
• UltiSnips Version: 3.1
• Python inside Vim: 3.8.10
• Docker repo/vimrc: https://github.com/SirVer/ultisnips/pull/1447