When running tig
$ tig
dyld: Library not loaded: /usr/local/opt/readline/lib/libreadline.7.dylib
Referenced from: /usr/local/bin/tig
Reason: image not found
Review ll /usr/local/opt/readline/lib/
and (accordingly):
sudo ln -s /usr/local/opt/readline/lib/libreadline.8.0.dylib /usr/local/opt/readline/lib/libreadline.7.dylib