fix(kubernetes): Fix NPE in bake manifest details (#7022)

If the bake manifest stage doesn't output any artifacts,
the stage fails to render due to an NPE. This is probably
rare as you'd generally want at least one artifact, but still
worth fixing.

app/scripts/modules/core/src/pipeline/config/stages/bakeManifest/BakeManifestDetailsTab.tsx

@@ -12,7 +12,7 @@ export class BakeManifestDetailsTab extends React.Component<IExecutionDetailsSec
   public static title = 'bakedManifest';
 
   public render() {
-    const bakedArtifacts: IArtifact[] = this.props.stage.context.artifacts.filter(
+    const bakedArtifacts: IArtifact[] = (this.props.stage.context.artifacts || []).filter(
       (a: IArtifact) => a.type === 'embedded/base64',
     );
     return (