Missing `nil` check for placement field in Policy health check

[dhaiducek]

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

When a Policy (from policy.open-cluster-management.io) has a status that is empty and non-nil (i.e. {}), the check for the status.placement field is throwing an error because it's doing a length check on a nil field:

<string>:10: __len undefined stack traceback: <string>:10: in main chunk [G]: ?

To Reproduce

Deploy a policy unattached to any placement.

Expected behavior

Health check does not throw an error.

Screenshots

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Version

(Version is the version tied to the PR where the code was updated in #21297 )

2.14.0

Logs

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[andrii-korotkov-verkada]

Is it in Go code? I think len of nil is just 0.

[dhaiducek]

@andrii-korotkov-verkada I was able to consistently reproduce it in the attached PR, #22057, so I think it's something about Lua. I don't know a whole lot about Lua, but it seems when obj.status is empty without any keys, I think the error comes when the script tries to do #obj.status.placement where since the placement key is already missing, so it's something more than just nil. I tried a trivial Lua program to confirm:

obj = {}
obj.status = {}

if #obj.status.placement > 0 then
    print("yay")
end

lua: main.lua:4: attempt to get length of a nil value (field 'placement')
stack traceback:
	main.lua:4: in main chunk
	[C]: in ? (exit status 1)

[andrii-korotkov-verkada]

Thanks! I initially didn't realize it's Lua code, so it makes sense.