Use a zsh shell, perhaps; though from your description you have done more than delete /bin/bash – How did you delete it?
zsh
sudo pacman -R bash
sudo pacman -S bash
Pacman does not rely on bash.
A possible workaround is to install a Terminal emulator that defaults to zsh, via Pamac-Manager (GUI) (Add/Remove Software), and then perform the previous pacman commands.
Yakuaka comes to mind, if you’re using KDE.
You don’t need to be sosmorttt to follow the logic.