fix(datasource/helm): Skip helm charts with no listed versions

lib/modules/datasource/helm/__fixtures__/index_emptypackage.yaml

@@ -0,0 +1,19 @@
+apiVersion: v1
+entries:
+  aerospike: []
+  ambassador:
+  - apiVersion: v1
+    appVersion: 0.70.1
+    created: 2019-06-02T08:56:36.119470813Z
+    description: A Helm chart for Datawire Ambassador
+    digest: 880002d74accfc9dab1debcc78c134fb4989e73ff84b137ce7aa92bf4d726297
+    engine: gotpl
+    home: https://www.getambassador.io/
+    icon: https://www.getambassador.io/images/logo.png
+    name: ambassador
+    sources:
+    - https://github.com/datawire/ambassador
+    - https://github.com/prometheus/statsd_exporter
+    urls:
+    - https://charts.helm.sh/stable/packages/ambassador-2.7.0.tgz
+    version: 2.7.0

lib/modules/datasource/helm/index.spec.ts

@@ -167,6 +167,24 @@ describe('modules/datasource/helm/index', () => {
       expect(releases).toMatchSnapshot();
     });
 
+    it('returns list of versions for other packages if one packages has no versions', async () => {
+      httpMock
+        .scope('https://example-repository.com')
+        .get('/index.yaml')
+        .reply(200, Fixtures.get('index_emptypackage.yaml'));
+      const releases = await getPkgReleases({
+        datasource: HelmDatasource.id,
+        packageName: 'ambassador',
+        registryUrls: ['https://example-repository.com'],
+      });
+      expect(releases).toMatchObject({
+        homepage: 'https://www.getambassador.io/',
+        registryUrl: 'https://example-repository.com',
+        sourceUrl: 'https://github.com/datawire/ambassador',
+        releases: expect.toBeArrayOfSize(1),
+      });
+    });
+
     it('adds trailing slash to subdirectories', async () => {
       httpMock
         .scope('https://example-repository.com')

lib/modules/datasource/helm/index.ts

@@ -60,6 +60,9 @@ export class HelmDatasource extends Datasource {
       }
       const result: HelmRepositoryData = {};
       for (const [name, releases] of Object.entries(doc.entries)) {
+        if (releases.length === 0) {
+          continue;
+        }
         const latestRelease = releases[0];
         const sourceUrl = findSourceUrl(latestRelease);
         result[name] = {