argocd app diff --local doesn't work if manifest type changed

[edude03]

If you are trying to resolve an environment-specific issue or have a one-off question about the edge case that does not require a feature then please consider asking a question in argocd slack channel.

Checklist:

• I've searched in the docs and FAQ for my answer: https://bit.ly/argocd-faq.
• I've included steps to reproduce the bug.
• I've pasted the output of argocd version.

Describe the bug

I had a helm chart for an internal app that was converted to use kustomize instead. I wanted to check that they were functionally identical by diffing them however argo complains that it can't find the chart.yaml file locally.

To Reproduce

• Deploy a helm chart
• Delete the chart.yaml
• run argocd diff $app --local

Expected behavior

I would expect that it would realize it's a kustomize directory and compare the rendered output of kustomize to the live manifest.

Version

argocd: v2.0.0-rc1+0ca643f
  BuildDate: 2021-03-19T21:30:25Z
  GitCommit: 0ca643f027b99e8a5b931bb8ee9df42c3e4b64bf
  GitTreeState: clean
  GoVersion: go1.16
  Compiler: gc
  Platform: darwin/amd64
WARN[0000] Failed to invoke grpc call. Use flag --grpc-web in grpc calls. To avoid this warning message, use flag --grpc-web.
argocd-server: v2.0.1+33eaf11
  BuildDate: 2021-04-15T22:31:51Z
  GitCommit: 33eaf11e3abd8c761c726e815cbb4b6af7dcb030
  GitTreeState: clean
  GoVersion: go1.16
  Compiler: gc
  Platform: linux/amd64
  Ksonnet Version: v0.13.1
  Kustomize Version: v3.9.4 2021-02-09T19:22:10Z
  Helm Version: v3.5.1+g32c2223
  Kubectl Version: v0.20.4
  Jsonnet Version: v0.17.0

Logs

FATA[0002] rpc error: code = Unknown desc = `helm template .
 --name-template myapp
 --namespace production
 --set image.tag=app-tag
 --api-versions v1
 [remove all the other apis for berevity]
 --include-crds` failed exit status 1: Error: Chart.yaml file is missing