ArgoCD doesn't handle malformed yaml files gracefully

[andoriyu]

Checklist:

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

Describe the bug

ArgoCD Application with auto-sync and pruning enabled. Someone checked in malformed yaml - indentations was wrong. ArgoCD silently-ish ignored that error and pruned the resources since it wasn't in "new state".

By silently ignored I mean the issue was only visible in logs and not in dashboard.

To Reproduce

• Create ArgoCD application with auto-sync and auto-prune enabled
• Add resources
• "break" the yaml file
• see resources get wiped

Expected behavior

ArgoCD would not try to apply such changes if yaml file is malformed.

Version

argocd: v1.3.6+89be1c9
  BuildDate: 2019-12-10T22:46:45Z
  GitCommit: 89be1c9ce6db0f727c81277c1cfdfb1e385bf248
  GitTreeState: clean
  GoVersion: go1.12.6
  Compiler: gc
  Platform: linux/amd64
argocd-server: v1.3.6+89be1c9
  BuildDate: 2019-12-10T22:47:48Z
  GitCommit: 89be1c9ce6db0f727c81277c1cfdfb1e385bf248
  GitTreeState: clean
  GoVersion: go1.12.6
  Compiler: gc
  Platform: linux/amd64
  Ksonnet Version: v0.13.1
  Kustomize Version: Version: {Version:kustomize/v3.2.1 GitCommit:d89b448c745937f0cf1936162f26a5aac688f840 BuildDate:2019-09-27T00:10:52Z GoOs:linux GoArch:amd64}
  Helm Version: v2.15.2
  Kubectl Version: v1.14.0

Logs

error: error parsing kafka.yaml: error converting YAML to JSON: yaml: line 207: did not find expected key

[todaywasawesome]

Closed with #2267