feat(analyzer): make sure ReplicaSetStatus has valid result

[DexterYan]

Description, Motivation and Context

• check result of analyzeReplicaSetStatus to be nil or not
• add missing nil result check for analyzeOneReplicaSetStatus

According user, we have another issue

  • Listing releases
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x3 pc=0x2ca2d13]

goroutine 1484 [running]:
github.com/replicatedhq/troubleshoot/pkg/analyze.(*AnalyzeReplicaSetStatus).Analyze(0xc001454ec0, 0x7323368?, 0xc001a1b2f0?)
    /var/cache/melange/gomodcache/github.com/replicatedhq/troubleshoot@v0.88.0/pkg/analyze/replicaset_status.go:50 +0x53

Checklist

• [x] New and existing tests pass locally with introduced changes.
• [ ] Tests for the changes have been added (for bug fixes / features)
• [x] The commit message(s) are informative and highlight any breaking changes
• [x] Any documentation required has been added/updated. For changes to https://troubleshoot.sh/ create a PR here

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No