Stockfish sometimes won't turn on for Safari users.

[nojoking]

Various Safari users have reported the same bug. The engine button won't stay on as pictured in the gif. This happens on all pages that have the engine button. The analysis board, puzzles, etc.

https://cdn.discordapp.com/attachments/352965935809691658/658015135067275284/lichess_bug.gif

[niklasf]

Safari 12.1.2 on Mac OS Sierra (outdated) for sure (happened today), and sure at 99% with Safari on IOS 13 (so Safari 13 I think)

[niklasf]

Failing to reproduce on Browserstack. Unlike the screen recording, the browsers even use WASM.

[niklasf]

{
    "diagnosticsVersion": 4,
    "navigator": {
        "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.1.2 Safari/605.1.15",
        "platform": "MacIntel",
        "chrome": false,
        "is64Bit": true
    },
    "wasm": {
        "WebAssembly": "object",
        "SharedArrayBuffer": "undefined",
        "Atomics": "undefined",
        "mvp": true,
        "structuredCloning": "ok"
    },
    "pnacl": {
        "mimeType": false
    },
    "needsBoardHeightFix": true,
    "hasTouchEvents": false,
    "animate": "undefined",
    "localStorage": {
        "client-eval-enabled": "0",
        "analyse.ceval.watchdog3.pnacl": null,
        "analyse.ceval.max-depth": "21",
        "analyse.ceval.multipv": "1",
        "analyse.ceval.threads": null,
        "analyse.ceval.hash-size": null,
        "analyse.ceval.infinite": null,
        "ceval.pool.start": "1577563833753",
        "ceval.fen": "start:0.20535523733420724",
        "just-notified": null,
        "push-subscribed": null,
        "grid": "1557063616138",
        "resize-nag": "1",
        "speech.enabled": null,
        "sound-volume": null,
        "surl6": "socket.lichess.org:9029"
    },
    "serviceWorker": {
        "navigator": true,
        "permissions": false,
        "Notification": true,
        "PushManager": false,
        "fetch": "function",
        "Notification.permission": "default"
    }
}

[niklasf]

Safari violating the localStorage spec, by firing events also in the original document (but only when there are multiple tabs).