k8s: ProcessEnvs appends env var before checking createEnvVarSource error

In pkg/k8s/deployer.go, ProcessEnvs (around line 635-639) calls createEnvVarSource, then immediately appends the returned valueFrom to envVars BEFORE checking the error:

valueFrom, err := createEnvVarSource(slices, referencedSecrets, referencedConfigMaps)
envVars = append(envVars, corev1.EnvVar{Name: *env.Name, ValueFrom: valueFrom})
if err != nil {
return nil, nil, err
}

While the function does return nil on error (so the caller discards the slice), this violates the standard Go error-handling pattern of checking errors before using return values. If any future refactoring changes the return to a continue, the partially-initialized entry stays in the list.

Additionally, createEnvFromSource and createEnvVarSource (lines 718-738 and 753-785) both validate that sourceName is non-empty only AFTER using it to construct resource references and inserting it into the referenced sets. The empty-string checks should be moved before the switch statement that uses sourceName.

Fix: reorder the append to happen after the error check, and move the empty-name validation earlier in both helper functions.