I'm sure this should not be done as a separate package, but as a simple function in .bashrc/.zshrc

  lscat(){
    if [ -d $1 ]; then
      ls $1
    elif [ -f $1 ]; then
      cat $1
    else
      echo "$1 is not valid path"
    fi
  }

Similarly, you can also use alias ls=lscat