TypeError: unsupported operand type(s) for +: 'NoneType' and 'list'
Again initialize bench using cmd below(for python 2) :
bench init --frappe-branch version-12 <your_bench_name>
Again initialize bench using cmd below(for python 3) :
bench init --frappe-branch version-12 --python /usr/bin/python3 <your_bench_name>