Docker:
Running of the `yarn run-tunnelbroker-service-in-sandbox` successfully built the app and the `~/tunnelbroker/` directory is used as the config files location.
Nix:
Enter the nix environment by using `nix develop` command.
Run `cmake -B build . && make -C build -j4` in the `services/tunnelbroker` directory to build the service.
Export the `TUNNELBROKER_CONFIG_FILE_DIRECTORY` environment variable with the directory of the service location (`services/tunnelbroker`).
Running of `build/bin/tunnelbroker` binary will not produce any config-related errors.
Exporting the wrong location using the `TUNNELBROKER_CONFIG_FILE_DIRECTORY` and running of `build/bin/tunnelbroker` will produce the config loading error on startup.