ArgoCD synchronization failed due to internal error

[alexmt]

Describe the bug

Following error is reported in operation message:

ComparisonError: <string>:3: attempt to compare nil with number stack traceback: <string>:3: in function 'checkReplicasStatus' <string>:75: in main chunk [G]: ?

To Reproduce
If we cannot reproduce, we cannot fix! Steps to reproduce the behavior:

1. Create an app using https://github.com/argoproj/argocd-example-apps repo and blue-green path.
2. Sync the app
3. See error

Version v1.1.0 unreleased

[alexmt]

Fixed by #1699