What should a timeline provider return when the fetch fails, and what do the reload policies mean as values?

Predict first

What do the success and the failure timelines contain?

import WidgetKit

struct Entry: TimelineEntry { let date: Date; let text: String }
enum Fetch: Error { case offline }

func build(now: Date, fetch: () throws -> [String], lastGood: String?) -> Timeline<Entry> {
    do {
        let items = try fetch()
        let entries = items.enumerated().map { Entry(date: now.addingTimeInterval(Double($0.offset) * 3600), text: $0.element) }
        return Timeline(entries: entries, policy: .atEnd)
    } catch {
        let stale = Entry(date: now, text: (lastGood ?? "No data") + " (stale)")
        return Timeline(entries: [stale], policy: .after(now.addingTimeInterval(900)))
    }
}
let now = Date(timeIntervalSince1970: 0)
let ok = build(now: now, fetch: { ["a", "b", "c"] }, lastGood: nil)
print(ok.entries.map { "\(Int($0.date.timeIntervalSince1970)):\($0.text)" }, ok.policy)
let bad = build(now: now, fetch: { throw Fetch.offline }, lastGood: "21°")
print(bad.entries.map { "\(Int($0.date.timeIntervalSince1970)):\($0.text)" }, bad.policy)

• Three hourly entries with .atEnd (date nil); then one stale entry "21° (stale)" with an after-15-minutes date
• Three entries in both cases
• The failure case returns an empty timeline