'Permission denied' error in module system deep dive tutorial

[srdtrk]

Problem

When going through the Module system deep dive tutorial, in section 2.6, running

nix-build eval.nix -A config.scripts.output
./result/bin/map

(even with sudo) returns

./result/bin/map: line 8: /nix/store/4cf5pb5pp11dg7kca57qfc2agig2ny7h-map.sh: Permission denied
feh WARNING: /tmp/feh_stdin_tna0vO - Invalid image file
feh: No loadable images specified.
See 'man feh' for detailed usage information

Willing to help? I'm not sure how to fix this as I'm new to nix. Please let me know if I'm missing something