nw2: window.on('close') crash and missing callback string during cmd + Q (OSX)

[nvedamurthy]

#7230
NWJS Version : nightly build 0.43.0 built on 12/10/2019 - https://dl.nwjs.io/live-build/nw43/20191210-162000/8f8b6a467/v0.43.0/
Operating System : OSX 10.15.1

Expected behavior

with --disable-features=nw2 argument, I am able to get the string quit passed in the callback as per the documentation here when cmd + q is pressed
http://docs.nwjs.io/en/latest/References/Window/#event-close
Also the app doesn't quit or crash, when the following code is executed in developer tools

nw.Window.get(window).on('close', function(osx_quit) {
    return;
});

Actual behavior

When the above code is executed in the developer tools.
cmd + Q is pressed , the flag in the callback is undefined and the app crashes. Few processes are still running in the activity monitor. Need to force quit the application to completely close.

How to reproduce

Download the sdk version (nwjs-sdk-v0.43.0-osx-x64.zip), in the above mentioned nightly build. In the developer tools, execute the following code:

nw.Window.get(window).on('close', function(osx) {
    var fs = require('fs');
    fs.writeFileSync("/Users/foo/test.txt", osx, function(err) {
        if(err) {
            console.log(err);
        }
    });
})

Press cmd + Q.
The app crashes. The file has undefined written in it instead of quit.

[rogerwang]

Thanks for reporting. This is fixed in git and will be available in the next nightly build.

CC #7242