<Leader>g in .vimrc are not functioning on macos

[fajarslvn]

When I use this "find . -type f | html-tool tags title | vim -" and want to go to title file with this command:
" grep recursively for word under cursor
nmap g :tabnew|read !grep -Hnr ''

it always ended with this:
:tabnew|read !grep -Hnr Example
shell returned 1

Press ENTER or type command to continue

and this error on the new tab: grep: (standard input): Bad file descriptor