Building a single package doesn't create external-kits/external-kit-metadata.json

[arnaldo2792]

What's the problem?

A single package is built in a clean core-kit fork by running:

PACKAGE=kernel-6_1 make twolier build-package

What really happened?

The build fails with this error:

 Unable to instantiate the builder: Failed to create build arguments due to a dependency error: Failed to read external kit metadata file '<my-path>/build/external-kits/external-kit-metadata.json': No such file or directory (os error 2)
Error while executing command, exit code: 101

Workaround

Run make ARCH=<> and CTRL+C the build so that the missing file is generated.