Returns a (bad) description of the warmup status of the server, based on request-specific state
function server_warmup_status(): string
string- - If the server appears to be warmed up, returns the empty string. Otherwise, returns a human-readable description of why the server is not warmed up. Note that this function checks a series of heuristics rather than anything definitive; returning '' for one request does not guarantee the same result for subsequent requests.