fix(helm): Fix unformatted error message

[AndiDog]

Description

Before:

$ skaffold render
std out err: %!(EXTRA *errors.errorString=Error: non-absolute URLs should be in form of repo_name/path_to_chart, got:

After:

$ skaffold render
Failed to render release: Error: non-absolute URLs should be in form of repo_name/path_to_chart, got:
 (releaseName="myproject", args=[template datawriter  --set image=<no value> -f k8s/dev/values-dev.yaml])

The example is an unhelpful error message coming from Helm, and <no value> was the hint I needed. (Side note: The --build-artifacts file had no builds, so the IMAGE_FULLY_QUALIFIED_* variables weren't filled in this case. Not relevant for the PR.)