List own projects, change directory and attach tmux easily

project.sh

#!/bin/bash

if [[ "$TERM" =~ "screen".* ]]; then
    echo "You have to detach tmux before continuing"
else
    if [ -z "$1" ]; then
        printf "\n\e[3mWhich project you want to open?\e[0m\n\n"

        ls -t ~/projects

        printf "\n> "

        read projectname
    else
        projectname=$1
    fi

    if [ ! -d "$HOME/projects/$projectname" ]; then
        printf "\e[0;31mCould not locate project folder for $projectname. You have to create it first.\e[0m\n"
    else
        cd ~/projects/$projectname
        tmux new-session -As $projectname
    fi
fi