What is making my configuration enter operator pending mode on new session? [duplicate]

Question

I've been reading through Learn Vimscript the Hard Way and trying some exercises. When I got into the autocommands/autogroups part, I've thought of creating an autocommand to automatically trim trailing white spaces from my C files. So I created the appropriate section on my .vimrc file and tested with a simple test.c program. The behavior is that when I write the file, the trailing spaces get deleted correctly. But if I write and quit Vim with ZZ or :wq, and then open the file again with vim test.c to check the results, the next key press deletes some characters. With I press j, it will delete to the next line, if I press k to the previous one. It's like I've just pressed d and I'm in operator pending mode for deletion.

What am I doing wrong?

My ~/.vimrc:

set number relativenumber
set hlsearch incsearch nowrapscan nowrap
set showcmd
set wildmenu wildignorecase complete+=d
set path+=**
set sidescroll=1 sidescrolloff=10

nnoremap <Leader>ev :split $MYVIMRC<CR>
nnoremap <Leader>sv :source $MYVIMRC<CR>
inoremap jk <Esc>
map <Leader>y "+y

noremap <Esc> <Nop>

augroup Ccfg
    autocmd!
    autocmd FileType c setlocal listchars=trail:.,tab:>-,extends:>,precedes:< list
    autocmd FileType c setlocal tabstop=4 shiftwidth=4 shiftround expandtab
    autocmd FileType c setlocal textwidth=80 colorcolumn=+1
    autocmd FileType c setlocal tagcase=match
    autocmd FileType c setlocal cscopetag
    autocmd FileType c setlocal breakindent
    autocmd FileType c iabbrev /*-*/ /*----------------------------------------------------------------------------*/
    autocmd BufWrite *.c,*.cpp,*.h %s/\v\s+$//e
augroup END

My test.c file:

#include <stdio.h>

int main(void)
{
    printf("Hello world!\n");    
    return 0;
}

Notice the trailing spaces after the printf call.

I'm trying to find a way to record my terminal session, but since I'm on Windows using Git Bash and it's Vim, I can't use asciinema or other solutions.

Answer 1

I've found out by trying different configurations that the culprit is the noremap <Esc> <Nop> line.

Thanks to @D. Ben Knoble for finding Why does the combination of remapping to cause strange characters to be automatically inserted when starting vim with startinsert? that explains that Esc is part of many special key combinations and remapping it to Nop interfere with those.