fix(helm): destructuring error when import chart with null props

[yuriy-yarosh]

Fixes cdk8s-team/cdk8s#2139 destructuring error.

[iliapolo]

@yuriy-yarosh could you also add a test for this scenario? best would be to just add the chart you identifier the issue with here:

cdk8s-cli/test/import/import-helm.test.ts

Lines 7 to 14 in 148ca1f

	describe.each([
	'helm:https://charts.bitnami.com/bitnami/[email protected]', // Contains schema and dependencies
	'helm:https://kubernetes.github.io/ingress-nginx/[email protected]', // Does not contain schema
	'helm:https://lacework.github.io/helm-charts/[email protected]',
	'helm:oci://registry-1.docker.io/bitnamicharts/[email protected]',
	'minio:=helm:https://operator.min.io/[email protected]',
	'helm:https://grafana.github.io/helm-charts/[email protected]',
	])('importing helm chart %s', (testChartUrl) => {

[iliapolo]

@yuriy-yarosh are you still available to see this through?

[yuriy-yarosh]

@iliapolo being conscripted, so things are a bit all over the place.
I'll take a look today.