Guard the empty-file case when loading CRDs

[arpitjain099]

A crds: entry that points at a zero-byte file crashes the build:

panic: runtime error: index out of range [0] with length 0

makeNameToApiMap looks at the first byte to decide between JSON and YAML:

if content[0] == '{' {
    err = json.Unmarshal(content, &result)
} else {
    err = yaml.Unmarshal(content, &result)
}

kustomization.yaml crds: takes relative paths, kusttarget.go hands each file to LoadConfigFromCRDs, and nothing checks the contents are non-empty on the way. So an empty file in that list panics rather than contributing no CRDs. A whitespace-only file does not trip it, since a space just routes to the YAML branch, which is what made this specific to zero-length files.

The fix uses the same shape the repo already uses in kyaml/openapi/openapi.go:

if len(content) > 0 && content[0] == '{' {

An empty file then goes to yaml.Unmarshal([]byte{}), which returns a nil map and no error, so it contributes nothing.

Test added next to TestLoadCRDs. It panics on master and passes with the change; go test ./internal/accumulator/ is green.

[kubernetes-prow]

Hi @arpitjain099. Thanks for your PR.

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[koba1t]

/ok-to-test

[saitejabandaru-in]

LGTM! This elegantly handles the empty file edge case and prevents the slice bounds out of range panic. The unit test also properly covers this scenario.

[saitejabandaru-in]

LGTM! This perfectly guards against the out-of-bounds index on empty files.

[kubernetes-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: arpitjain099, saitejabandaru-in
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