Checkers Double Jump Crashes Game

[jackjbridge-socceranalytics]

Describe the bug
In online multiplayer mode, the checkers game crashes every time a user faces a double jump scenario.

To Reproduce
Steps to reproduce the behavior:

1. Set up a multiplayer online checkers game
2. Set up a double jump scenario (spot where one user would have two continuous jumps
3. Perform the first jump

Expected behavior
The user should be able to make the double jump without the page crashing

Desktop (please complete the following information):

• Mac OS
• Chrome

[vdfdev]

Hi @jackjbridge-socceranalytics, thanks for reporting this issue!

I tried one game with the double jump scenario and it worked for me. Can you please send a screenshot with the board configuration which this happens? It would help us a lot to reproduce the issue.

I am also wondering if it could be related to other UX-related issues that we will fix soon

[jackjbridge-socceranalytics]

Hi! No problem. Thanks for looking into it! I recreated here with this gif.

[leocaseiro]

I confirm I was able to replicate the exact same error. Any jump that needs to be done twice, BOOM!

[leocaseiro]

This is the error I'm getting:

react_devtools_backend.js:2430 TypeError: n.sum is not a function

This is the broken function
var f = n.sum(c.multiply(p));

Which leads to https://github.com/freeboardgames/FreeBoardGames.org/blob/master/web/src/games/checkers/game.ts#L102

function g(t, e, r, n) {
    var o, a = [], i = !1, s = l(r.isKing ? m : y[e]);
    try {
        for (s.s(); !(o = s.n()).done; )
            for (var c = o.value, u = null, p = 1; r.isKing || p < 3; p++) {
                var f = n.sum(c.multiply(p));
                if (!f.inBounds())
                    break;
                var h = t.board[f.toIndex()];
                if (null !== h && h.playerID === e)
                    break;
                if (null !== h && h.playerID !== e) {
                    if (u)
                        break;
                    u = f
                }
                if (null === h) {
                    if (a.push({
                        from: n,
                        to: f,
                        jumped: u
                    }),
                    u) {
                        i = !0;
                        break
                    }
                    if (!r.isKing)
                        break
                }
            }
    } catch (d) {
        s.e(d)
    } finally {
        s.f()
    }
    return {
        moves: a,
        jumped: i
    }
}

checkers-error.mp4

[leocaseiro]

Hi @mateusazis, for my quick investigation I'm suspecting of this PR e0e6f2b

Would you mind testing that scenario, please?

Thanks

[mateusazis]

This seems to be caused because I'm passing an objects with methods to the game state, but the class is lost when it gets serialized back-and-forth between client and server. It does not seem to happen in local mode.

I am having some trouble reproducing this in tests, but converting (serialized data=>class) should fix it. Sending a PR.

[vdfdev]

Thanks @leocaseiro for debugging and @mateusazis for the quick fix, this is in prod now!